48FK,JK034-104
48FM078-104
50FK,FY,JK,JY034-104
50FM,FS078-104
Variable-Air Volume Rooftop Units
Controls Operation,
and Troubleshooting
CONTENTS
Page
Page
Control From Remote Building Management
SAFETY CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . 2
System (BMS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
GENERAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
Rooftop Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
VAV Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Processor Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
• P1 — SUPPLY-AIR SET POINT
• OCCUPIED/UNOCCUPIED
• NIGHT SETBACK CONTROL
• UNIT SUPPLY AIR SET POINT ADJUSTMENT
• DEMAND UNIT (1-STAGE OR 2-STAGE)
• SUPPLY DUCT PRESSURE SET POINT ADJUSTMENT
• EXTERNAL ALARM SIGNAL
• P2 — ECONOMIZER POSITION
• P3 — RESET LIMIT
• REMOTE ECONOMIZER CONTROL
Smoke Control Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . 21
• FIRE SHUTDOWN MODE
• P4 — DEMAND LIMIT
• P5 — ECONOMIZER MINIMUM POSITION
• P6 — WARM-UP SET POINT
• PRESSURIZATION MODE
• P7 — SASP RESET TEMPERATURE
• EVACUATION MODE
• PROCESSOR BOARD OUTPUTS
• CONFIGURATION HEADER AND DIP SWITCH
ASSEMBLY
Relay Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Display Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
• T1 — SUPPLY-AIR TEMPERATURE THERMISTOR
• T2 — RETURN-AIR TEMPERATURE THERMISTOR
• T3 — SATURATED CONDENSING TEMPERATURE,
CIRCUIT 1
• SMOKE PURGE MODE
• INSTALLATION
• CONFIGURATION
• OPERATING SEQUENCE
Air Pressure Tubing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
• INLET GUIDE VANES
• SUPPLY FAN VARIABLE FREQUENCY DRIVE
• MODULATING POWER EXHAUST
START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25-31
Initial Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Configuration Header . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
DIP Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Adjusting Set Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Potentiometers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Supply Fan Control with IGV Option . . . . . . . . . . . . 28
Supply Fan Control with VFD Option . . . . . . . . . . . . 28
Modulating Power Exhaust Option or
Accessory) (48FK,JK and 50FK,JK Units) . . . . . 30
High Capacity Power Exhaust
(48FM and 50FM,FS Units) . . . . . . . . . . . . . . . . . . . . 30
START UNIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31-34
Quick Test Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
• T4 — SATURATED CONDENSING TEMPERATURE,
CIRCUIT 2
• T10 — RESET TEMPERATURE
Compressor Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . 7
• CONTROL RELAY (CR)
Accessory Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
• P3 — RESET LIMIT
• P5 — ECONOMIZER MINIMUM POSITION
• P6 — MORNING WARM-UP TEMPERATURE
Single-Step Demand Unit. . . . . . . . . . . . . . . . . . . . . . . . . 7
Demand Limit Control Module (DLCM) . . . . . . . . . . . 7
Economizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
• ENTHALPY CONTROL
• DIFFERENTIAL ENTHALPY
OPERATING INFORMATION. . . . . . . . . . . . . . . . . . 34-44
Digital Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
• CODES 0 THROUGH 8, CAPACITY STEPS
• CODES 20 THROUGH 30 AND 88, OPERATIONAL
STATUS
Supply Fan Variable Frequency Drive (VFD). . . . . 12
High Capacity Modulating Power
Exhaust Variable Frequency Drive . . . . . . . . . . . . 12
Temperature Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
CONTROLS INSTALLATION. . . . . . . . . . . . . . . . . . 13-25
Control Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
• NIGHT SETBACK THERMOSTAT
• SPACE TEMPERATURE RESET ACCESSORY
(50DJ900021)
• CODES 51 THROUGH 87, DIAGNOSTIC
INFORMATION
Operating Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
• SIZE 034, 038 AND 048-088 UNITS
• SIZE 044 UNITS
• SIZE 104 UNITS
Space Temperature Reset . . . . . . . . . . . . . . . . . . . . . . 13
• INSTALLATION
Head Pressure Control . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Supply Fan Control with IGV . . . . . . . . . . . . . . . . . . . . 38
Supply Fan Control with VFD. . . . . . . . . . . . . . . . . . . . 38
Modulating Power Exhaust (48FK,JK and
50FK,JK Units Option or Accessory). . . . . . . . . . 38
High Capacity Modulating Power Exhaust
(48FM and 50FM,FS Units) . . . . . . . . . . . . . . . . . . . . 38
Unit Staging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
• CONFIGURATION
• OPERATING SEQUENCE
Demand Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
• SINGLE-STEP DEMAND LIMIT
• TWO-STEP DEMAND LIMIT
• INSTALLATION
• CONFIGURATION
• OPERATING SEQUENCE
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 534-763 Printed in U.S.A. Form 48/50F,J-3T Pg 1 3-00 Replaces: 48/50F,J-1T
Book 1
1
Tab 1a 1b
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The VAV control system monitors and controls the follow-
ing functions of the rooftop unit:
Several status switches are also monitored. These switches
are connected to the processor at pin terminal connector J2. See
Fig. 3 and Table 2.
In addition to the unit status switch inputs, the processor
board also accepts inputs from several potentiometers. These
potentiometers control various operational characteristics of
the system. Inputs are received by the processor through pin
terminal connector J3. See Fig. 4.
•
•
•
•
•
•
•
•
supply-air temperature (unit capacity)
morning warm-up or electric heat (if equipped)
head pressure control, fan cycling
economizer position
diagnostic display
unit check-out (quick test)
supply air temperature reset (if equipped)
demand limiting (if equipped)
Table 1 — Pin Terminal Connector J1
Thermistor Inputs
Processor Board — The processor board, shown in
Fig. 1, contains the logic and the necessary hardware to drive
the outputs and the display board. The processor board is en-
closed by a sheet metal cover and a heater. The heater is con-
trolled by a thermostat to keep the processor temperature above
32 F (0° C). All electrical connections are made to the proces-
sor board through wire and ribbon cables.
CONNECTOR J1
TERMINAL NO.
TEMPERATURE
INPUT
Reset Temperature*
Saturated Condensing
Temp., Circuit 2
Saturated Condensing
Temp., Circuit 1
UNIT SIZE
034-104
1,2
T10
14,15
T4
16,17
T3
Several temperature inputs are connected to the processor.
There are either 4 or 5 thermistors (depending on the field-
installed accessories) which input temperature data into the
processor through pin terminal connector J1. See Table 1 and
Fig. 2.
18,19
20,21
Return-Air Temperature
Supply-AirTemperature
T2
T1
LEGEND
T — Thermistor
*If equipped with accessory temperature reset package.
NOTE: Terminal numbers 3-13 are not used on these units.
LEGEND
DIP
EPPOM — Erasable, Programmable Read-Only Memory
EXV — Electronic Expansion Valve
— Dual In-Line Package
*EPROM HT204485-1-XX where “XX” is the current revision
number.
NOTE: Processor Board is positioned in unit with J3 and J10
connections at the bottom.
Do not remove label covering EPROM. Removal causes pro-
gram to be erased.
Fig. 1 — Processor Board
3
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LEGEND
CR
EC
—
—
Control Relay
Enthalpy Control
LEGEND
LPS — Low-Pressure Switch
T
—
Thermistor
Field Wiring
Accessory
Fig. 3 — Pin Terminal Connector J2
Status Switch Inputs
Fig. 2 — Pin Terminal Connector J1
Thermistor Inputs
Table 2 — Pin Terminal Connector J2
Status Switch Inputs
CONNECTOR J2
TERMINAL NO.
UNIT SIZE
034-104
STATUS SWITCH
Oil Pressure,
Circuit 2
Oil Pressure,
Circuit 1
Loss of Charge,
Circuit 2
1,2
Jumpered
Jumpered
LPS2
3,4
7,8
Loss of Charge,
Circuit 1
9,10
LPS1
Economizer
Changeover
Compressor Fault
Signal
Compressor Fault
Signal
13,14
15,20
15,24
LEGEND
EC
CR2
CR1
LEGEND
IN
— Input
Factory Wiring
Field Wiring
Accessory
CR — Control Relay
P
— Potentiometer
— Return
EC — Enthalpy Control
RNT
SW
LPS — Low-Pressure Switch
— Switch
NOTE: Terminal numbers 5, 6, 11, 12, 16-19, and 21-23 are not used
on these units.
Fig. 4 — Pin Terminal Connector J3
Potentiometer Inputs
4
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All of the potentiometers must be set before the unit is start-
ed in order for the unit to function properly. See Start Up, Po-
tentiometers section on page 27 for information on establishing
set points. Each of the potentiometers has a valid range that is
used by the control. The valid range is defined as the potenti-
ometer’s resistance value that the control will not consider to
be in error. This is usually between 10% and 90% of the poten-
tiometer’s total resistance. The control has been programmed
to accept an operational range for the potentiometer, which
may not be the same as the valid range.
CONFIGURATION HEADER AND DIP SWITCH ASSEM-
BLY — The processor board is programmed to control a vari-
ety of air conditioning units. To tailor the processor to the par-
ticular unit being controlled, 2 devices are used. One is the
configuration header, and the other is the DIP switch assembly.
The configuration header (part no. 30GB660001) is a series
of 8 small wires that are broken or unbroken in a pattern to in-
dicate several unique characteristics of the unit. The configura-
tion header is factory set and should not be changed. Changing
the factory setting may cause the unit to malfunction.
The DIP switches configure the unit for several field-in-
stalled options, as well as for several other options that may be
unique to the unit. The DIP switches are located under a plastic
enclosure which must be removed for access. The switches can
be field adjusted, but must be adjusted only when the unit con-
trol circuit breaker is off.
The potentiometer locations and functions are as follows:
P1 — SUPPLY-AIR SET POINT — This potentiometer is
located on the display board. The supply-air set point is the
cooling mode control temperature which the VAV control sys-
tem will attempt to maintain at Thermistor T1 by control of
economizer position and/or cycling unloaders and compres-
sors.
P2 — ECONOMIZER POSITION — Economizer feedback
potentiometer is located on the economizer motor. The micro-
processor is programmed to indicate an alarm if the travel dur-
ing initialization is less than 10% of the total potentiometer’s
resistance. An alarm condition will also be signaled if the
potentiometer fails during operation, indicating that the
damper blades are stuck. If either situation occurs, the proces-
sor will try to drive the economizer dampers closed.
P3 — RESET LIMIT — This potentiometer is located on the
accessory board (provided standard from the factory) in the
unit main control box and establishes the maximum amount of
reset that can be applied to the supply-air set point (P1). Reset
is limited by the P1 default of 70 F. This potentiometer is used
only when accessory, field-installed temperature reset is used.
If temperature reset is used, DIP (dual, in-line package) switch
2 must be in the ON position.
P4 — DEMAND LIMIT — This potentiometer is located near
TRAN4 in the unit control box. The demand limit potentiome-
ter is used only if accessory, field-installed demand limit is
used, and if DIP switch 5 is in the ON position. For single-step
demand limit, a field-installed 5 to 20 Kohm potentiometer and
switch must be used.
P5 — ECONOMIZER MINIMUM POSITION — This
potentiometer is on the accessory board (provided standard
from the factory) located in the unit main control box. This
potentiometer specifies the minimum opening position for the
optional economizer. If a fault condition is detected by the pro-
cessor, an alarm condition will be signaled and the economizer
dampers will close.
P6 — WARM-UP SET POINT — This potentiometer is on
the accessory board (provided standard from the factory)
located in the unit main control box. This potentiometer estab-
lishes the set point temperature for the Morning Warm-Up
function. When the temperature is reached, Morning Warm-Up
is terminated and VAV operation begins. DIP switch 4 must be
in the ON position if morning warm-up heat is to be used.
Relay Board — The relay board is used to control 24-v
and 115-v loads. See Fig. 5. The relay board is connected to the
processor board by a ribbon cable at pin J9. Electrical connec-
tions to the relay board are made through pins J5 (115 v) and J6
(24 v). The relay board has eight 24-v relays and five 115-v re-
lays. See Table 3.
Display Board — The display board is located in the
main unit control box and is connected to the J10 port of the
processor board through a ribbon cable. The display board con-
tains the supply-air set point potentiometer P1; a 2-digit, LED
display; and the display button (see Fig. 6). The LED display is
used to convey the operating information and operational error
codes.
Thermistors — The processor uses up to 5 thermistors to
sense the temperatures at various points in the system. See Ta-
ble 1 and Fig. 7-14. All the thermistors have identical tempera-
ture versus resistance and voltage drop characteristics, and are
monitored by the processor for a short or open circuit. The val-
id range for a thermistor is 362,640 to 219 ohms. Thermistor
details and locations are as follows:
T1 — SUPPLY-AIR TEMPERATURE THERMISTOR —
This thermistor is located in the unit supply fan discharge. It
provides information for the processor to stage the number of
capacity steps required to maintain a desired supply-air tem-
perature.
T2 — RETURN-AIR TEMPERATURE THERMISTOR —
This thermistor is located in the mixed-air portion of the unit
cabinet. The thermistor’s primary function is to provide morn-
ing warm-up information. This sensor will also provide differ-
ential information for the processor during cooling operation
(such as the rate of change for a capacity step).
T3 — SATURATED CONDENSING TEMPERATURE,
CIRCUIT 1 — This thermistor is located on the condenser coil
return bend. See Fig. 13 and 14. It controls the staging of the
unit condenser fans based on the condensing temperature of
the refrigerant at the designated position on the condenser coil.
P7 — SASP (SUPPLY AIR SET POINT) RESET TEMPER-
ATURE — This 10 Kohm potentiometer is used only if the
accessory, field-installed temperature reset package is installed.
This potentiometer determines the temperature at which reset
will begin. It is located on the accessory temperature reset
board. DIP switch 2 must be in the ON position to enable
SASP reset.
PROCESSOR BOARD OUTPUTS — The processor board
also controls outputs through the relay board. The relay board
plugs into the processor board using a ribbon cable.
T4 — SATURATED CONDENSING TEMPERATURE,
CIRCUIT 2 — This thermistor is located on the condenser coil
return bend. See Fig. 13 and 14. It controls the staging of the
unit condenser fans based on the condensing temperature of
the refrigerant at the designated position on the condenser coil.
T10 — RESET TEMPERATURE — This thermistor is used
only if the accessory temperature reset package is used. It pro-
vides occupied space temperature information to the processor,
which determines whether or not reset is required. The ther-
mistor is remotely mounted outside the unit in the conditioned
space.
In addition, the processor board controls the display board. The
display board is connected to the processor board by a ribbon
cable, and has an LED (light-emitting diode) display showing
the status of the unit and diagnostic information.
5
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Table 3 — Output Pin and Terminal Assignments
OUTPUT PIN-
TERMINAL
NAME
RATING
DEVICE
CR1
Stage 1
J6-1
J6-2
Compressor Relay (K1)*
Stage 2
U2**
Compressor Relay (K2)*
Stage 3
J6-3
J6-4
J6-5
U1
Not Used
CR2
Compressor Relay (K3)*
Compressor Relay (K4)†
Stage 5
Compressor Relay (K5)†
24 vac
Stage 6
Compressor Relay (K6)†
J6-6
Not Used
J6-7
J6-8
J5-1
J5-2
Economizer Open Relay (K7)
Economizer Close Relay (K8)
Supply Fan Relay (K9)
EOR
ECR
IFC
Morning Warm-Up Relay (K10)
HIR
Stage 1 Condenser
Fan Relay (K11)
J5-3
OFC2/OFC3††
115 vac
Stage 2 Condenser
Fan Relay (K12)
External Alarm Relay (K13)
J5-4
J5-5
OFC4||
ALM
LEGEND
*Circuit 1.
†Circuit 2.
ALM — Alarm
**U2 is not used on 044 units.
CR — Control Relay
††OFC2 on 034-048 units; OFC3 on 054-104 units.
ECR — Economizer Close Relay
EOR — Economizer Open Relay
HIR — Heat Interlock Relay
||Used on 054-104 units only.
IFC — Indoor (Evaporator) Fan Contactor
OFC — Outdoor (Condenser) Fan Contactor
U
— Unloader
LEGEND
CR — Control Relay
J
K
— Terminal Pin Connectors
— Relay
Fig. 5 — Relay Board
6
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P1 SUPPLY AIR
SET POINT
POTENTIMETER
TWO-DIGIT
DISPLAY
DISPLAY
BUTTON
P3 — RESET LIMIT — The processor board is programmed
for occupied space temperature reset. In order for reset to
work, the accessory temperature reset board must be used.
Potentiometer P3 is the maximum set point temperature to
which the supply air can be reset.
P5 — ECONOMIZER MINIMUM POSITION — This
potentiometer controls the set point for the minimum position
of the economizer.
P6 — MORNING WARM-UP TEMPERATURE — This
potentiometer controls the morning warm-up temperature set
point.
Single-Step Demand Limit — The single step de-
mand limit provides a means to limit the capacity of the VAV
unit using an external switch. Single step demand limit will
limit the compressor displacement based on the ratio of the
wiper arm to the full scale resistance. The exact percentage of
capacity reduction differs depending on the number of capacity
steps.
A 3-wire, 5 to 20 Kohm, field-supplied potentiometer (P4)
is required for this option. The potentiometer should be wired
to the processor J3 connections. In order to control the demand
limit, the wiper arm of the potentiometer should be switched
open and closed based on the demand limit requirement. The
control switch is also field-supplied and installed.
If the wiper arm wire is open, all capacity stages can be
used. When the wiper arm wire is closed, the capacity is re-
duced by the amount set on potentiometer P4.
Fig. 6 — Display/Set Point Board
Compressor Operation
CONTROL RELAY (CR) — This relay provides information
to the processor about compressor operation (one control relay
per compressor). The relay controls and protects the compres-
sor and also controls the crankcase heater.
Demand Limit Control Module (DLCM) — The
DLCM provides a 2-step demand limit control using an exter-
nal switch. The first step is between 50% and 100% of the
maximum compressor displacement. See Fig. 16. The second
step is between 0% and 49% of the maximum compressor dis-
placement. The exact percentage differs depending on the
number of capacity steps.
Two adjustable potentiometers are used to set the 2 demand
limit points. Potentiometer P1 is used to set a demand limit
between 50% and 100% of the unit capacity. Potentiometer P2
is used to set a demand limit between 0% and 49% of unit
capacity.
If no power is supplied to the demand limit control module,
all capacity stages can be used. When power is supplied to ter-
minal IN1 only, the first step of the demand limit control is en-
ergized and the capacity is reduced by the amount set on poten-
tiometer P1. When power is supplied to terminal IN2 only, or
to both IN1 and IN2, the capacity is reduced by the amount set
on potentiometer P2.
A control signal to check the safety statuses and to start the
compressor is sent from the relay board. This signal travels
through all of the safeties: the high-pressure switch, and the in-
ternal protector (where used) and on to the control relay coil.
Once the control relay coil has been energized, the control re-
lay completes a feedback circuit for the processor, informs the
processor of the status of the compressor safeties, energizes the
compressor contactor coil, and deenergizes the crankcase heat-
ers. A fault will be detected by the processor if the control relay
opens during operation or startup. The processor will lock the
compressor or the circuit off by deenergizing the appropriate
relay(s) on the relay board and energizing an alarm signal.
Accessory Board — The accessory board is standard
(factory supplied) in the VAV rooftop units. See Fig. 15. This
board is located in the control box of each unit. Each board has
a prewired connector supplied with it to connect directly to the
processor board. It has 3 potentiometers: P3, P5, and P6.
7
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GAS SECTION
(48FK,JK ONLY)
HORIZONTAL SUPPLY SECTION
(50FY,JY ONLY) AND EXTENDED
PLENUM SECTION (50FKX,FKY,JKX,JKY)
Fig. 7 — Thermistor T1 Location, 48FK,JK, 50FY,JY and 50FKX,FKY,JKX,JKY 034-048 Units
FAN DISCHARGE/ELECTRIC HEAT SECTION
Fig. 8 — Thermistor T1 Location, 50FK,JK034-048 Units
8
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HORIZONTAL SUPPLY SECTION (50FS,FY,JY)
AND EXTENDED
PLENUM SECTION (50FKX,FKY,FMX,FMY,JKX,JKY)
GAS SECTION
(48FK,FM,JK)
Fig. 9 — Thermistor T1 Location, 48FK,FM,JK, 50JY and
50JKX,JKY 054-074 Units and 50FKX,FKY,FMX,FMY and 50FS,FY054-104 Units
FAN DISCHARGE/ELECTRIC HEAT SECTION
Fig. 10 — Thermistor T1 Location, 50FK,JK054-074 Units
9
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BAG
FILTERS
STANDARD
FILTERS
Fig. 11 — Thermistor T2 Location, Size 034-048 Units
Fig. 13 — Thermistor T3 and T4 Locations,
Size 034-048 Units
ENTHALPY CONTROL
48FK,JK and 50FK,FY,JK,JY Units — Outside air enthalpy
control is standard with the factory-installed economizer op-
tion. Enthalpy is sensed by a controller located behind the end
outside air hood. The control can be accessed by removing the
upper hood filter. See Fig. 17.
48FM and 50FM,FS Units — The control is located on the
metal upright between the two economizer hoods, on the right
hand side of the unit, and can be accessed by removing the fil-
ter on either economizer hood.
DIFFERENTIAL ENTHALPY — Added efficiencies in econ-
omizer control can be gained by installing a differential en-
thalpy sensor in the return air duct. When differential enthalpy
control is installed, the economizer control will use the air
stream with lower enthalpy (outside air or return air) to provide
for lower compressor operating costs during integrated econo-
mizer cycle operation. The differential enthalpy sensor is
installed in the return-air duct.
BAG FILTERS
(054-074 Only)
STANDARD FILTERS AND
PLEATED FILTERS
Fig. 12 — Thermistor T2 Location, Size 034-048 Units
Economizer — Economizer control is used to control the
outside and return air dampers of the unit, to satisfy space cool-
ing demand using all outside air (when permitted), and to satis-
fy cooling in conjunction with compressor operation (when
conditions permit). During Occupied periods without cooling
demand, the outside-air dampers will be at the user-configured
Minimum Damper Position (at P5 on accessory board). During
Unoccupied periods, the outside-air dampers will be closed.
The economizer is a standard feature on 48FM and
50FM,FS units and is available as a factory-installed option on
48FK,JK and 50FK,FY,JK,JY units.
The user can install an accessory differential enthalpy sen-
sor to enhance economizer control. Refer to the installation
section for field wiring of the sensor.
10
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054 UNITS
064, 074, 078 UNITS
088, 104 UNITS
Fig. 14 — Thermistor T3 and T4 Locations, Size 054-104 Units
11
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The unit is supplied with a pressure transducer capable of
measuring from 0.0 to 5.0 in. wg. The pressure transducer will
send a 4 to 20 mA signal to the VFD to modulate the speed of
the indoor fan motor to precisely control the fan to the desired
static pressure set point. The VFD is factory set at 2.5 in. wg
duct static pressure. Refer to the Operating Sequence section
for more information on the VFD.
The VFD has been programmed and wired at the factory for
this application. No further adjustments (except for Duct Static
Pressure Set Point) should be necessary at start-up. Factory
jumper wire configurations are shown in the Supply Fan Con-
trol with VFD Option section on page 28.
A separate service manual for the factory-installed VFD is
supplied with each unit. Refer to the VFD manual for more in-
formation on the VFD controls.
LEGEND
High Capacity Modulating Power Exhaust
Variable Frequency Drive (48FM and 50FM,FS
Units Only) — The power exhaust VFD (PE VFD) is used
to modulate the power exhaust fan motor no. 1 and stage the
power exhaust fan motor no. 2 in order to maintain building
static pressure. The PE VFD is located at the return air end of
the unit of the opposite side from the auxiliary control box and
can be accessed by opening the access door.
The unit is supplied with a pressure transducer capable of
measuring from –0.5 to +0.5 in. wg. The pressure transducer
will send a 4 to 20 mA signal to the PE VFD to modulate the
speed of the power exhaust motor no. 1 and also stage on/off
the power exhaust motor no. 2 to precisely maintain the desired
building pressure set point. The PE VFD is factory set at
0 in. wg. Refer to Operating Sequence section for more infor-
mation on the PE VFD.
ECON — Economizer
MIN
P
— Minimum
— Potentiometer
VAV — Variable-Air
Volume
Fig. 15 — Accessory Relay Board
(Standard; Factory Supplied)
The PE VFD has been programmed and wired at the factory
for this application. No further adjustments (except for Build-
ing Pressure Set Point) should be necessary at start-up. Factory
jumper wire configurations are shown in the Power Exhaust
Variable Frequency Drive section in the Troubleshooting sec-
tion on page 55.
LEGEND
IC
IN
P
— Integrated Circuit
— Input
— Potentiometer
RTN — Return
Fig. 16 — Two-Step Demand Limit Module
Fig. 18 — Variable Frequency Drive,
Sizes 034-048 and 078-104
Fig. 17 — Enthalpy Sensor Location
(48FK,JK and 50FK,FY,JK,JY Units Only)
Supply Fan Variable Frequency Drive
(VFD) — The optional VFD is used to modulate supply fan
airflow to maintain duct static pressure on VAV applications.
The VFD is located in the supply fan section (see Fig. 18 and
19), and can be accessed by opening the fan section access
door.
Fig. 19 — Variable Frequency Drive, Sizes 054-074
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A separate service manual for the factory installed PE VFD
is supplied with each unit. Refer to PE VFD manual for more
information on the PE VFD.
control box. When unit goes into Heating mode, interlock relay
is energized providing switch closure or opening (depending
on how field power source is set up) to open the room termi-
nals. Field connections for interlock relays are terminals 3 and
4 (for normally open contacts) and terminals 3 and 7 (for nor-
mally closed contacts) on terminal block 3 (sizes 034-048) or
terminal block 4 (sizes 054-104). See Fig. 24. Note that a field-
supplied power source is required.
There are no required 115-volt field wiring connections,
therefore no provisions have been made in the unit for running
115-volt wiring. If any of the field-installed options requiring
115-volt connections are desired, the unit must be modified in
the field for 115-volt wiring.
NIGHT SETBACK THERMOSTAT — Wire field-supplied
thermostat (suitable for 24-v circuit) between terminals 1 and 2
on terminal block 3 (sizes 034-048) or terminal block 4
(sizes 054-104). This thermostat is used to bypass the time-
clock occupied/unoccupied switch and is used to operate unit
during unoccupied times at more economical temperatures.
(See Fig. 23.)
SPACE TEMPERATURE RESET ACCESSORY (50DJ900021)
— Consists of a thermistor (T10) and a reset board with a potenti-
ometer (P7) that is used to set space temperature at which reset
starts. Mount reset board in unit control box or other convenient
place. Wire thermistor in series with P7 and connect to terminals
12 and 15 on terminal block 3 (sizes 034-048) or terminal block 4
(sizes 054-104) in unit control box. If there is a long run to condi-
tioned space, it is necessary to splice additional wire to thermistor.
The reset board has 2 pressure connectors for field wiring. (See
Fig. 25.)
Temperature Reset — Accessory temperature reset al-
lows the unit to automatically adjust (‘‘reset’’) the supply-air
temperature set point to a higher value once most of the space
cooling load has been met. When the space conditions are sat-
isfied, the VAV terminals will close to the minimum position.
All VAV units will sense the decrease in actual supply-air tem-
perature and the unit controls respond by reducing capacity
stages to maintain user-established supply-air set point temper-
ature. When VAV units are also equipped with optional supply
duct pressure controls (either inlet guide vanes [IGV] or vari-
able frequency drive package), the unit also senses an increase
in duct static pressure and responds by closing IGV dampers or
slowing fan wheel speed to maintain user-configured set points
for supply duct pressure. Allowing the supply-air temperature
to be reset to a higher value maintains air circulation in the
space without costly overcooling.
The accessory package is required for temperature reset.
The accessory includes:
•
•
thermistor T10, to monitor space temperature
reset temperature potentiometer P7, to establish start
temperature for reset operation
reset limit potentiometer P3, to establish maximum level
of modified supply-air temperature
•
More than one space sensor may be used if an average
space temperature is desired for initiating temperature reset.
Refer to installation section for sensor part number and wiring
schematic.
Space Temperature Reset
INSTALLATION — Install the accessory temperature reset
package in accordance with instructions provided with the
accessory kit.
Mount the reset board in the unit control box (or other suit-
able location) per instructions.
Locate the thermistor T10 in a suitable location in the occu-
pied space per instructions.
Temperature reset will start when space temperature (at
T10) drops to the set point at P7. When Temperature Reset
is active, the LED (light-emitting diode) display will show
code 21 . Automatic adjustment of supply-air temperature set
point will end when modified SASP equals reset limit set point
at P3. (See formula for automatic modification of SASP in
Controls Installation, Space Temperature Reset section on this
page.)
Wire T10 to the reset board and to the unit control terminal
block per Fig. 25. Wire the other terminal on the reset board to
the unit control terminal block per Fig. 25.
If multiple sensors are required to average the space temper-
ature, see Fig. 26. Use only Carrier Part Number HH79NZ014
sensor, in arrangements of 4 or 9 sensors, with total wiring not
to exceed 1000 ft.
CONTROLS INSTALLATION
The VAV units may be used in applications with additional
control features, options, or accessories. Refer to the appropri-
ate accessory installation instructions for more information on
installing that accessory. Unit control box component arrange-
ment is shown in Fig. 20-22. Control options and accessories
available for VAV units are:
To enable reset function, change DIP (dual in-line package)
switch 2 to position ON. (Disconnect control power before
changing DIP switch positions; reconnect power after all
changes have been made.)
CONFIGURATION — Set points for reset operation are
established at potentiometers P7 and P3 (on the reset board).
Potentiometer P7 — Reset temperature set point (temperature
at which reset function will start). Maximum of 80 F, mini-
mum 0° F. Set below normal room cooling set point level to
sense overcooling in the occupied space.
NOTE: It is difficult to accurately set the P7 potentiometer to
the desired set point. Use the procedure below.
•
•
•
•
•
•
•
•
•
•
•
•
smoke control modes
differential enthalpy sensor
electric heaters (sizes 034-074 only)
modulating power exhaust
Motormaster® I control
space temperature reset
night setback thermostat (field-supplied)
single step demand limit
two-step demand limit
inlet guide vanes
variable frequency drive
variable frequency drive remote display kit
Control Wiring — A switch or timeclock (field supplied)
must be wired in to control when unit will go into and out of
Occupied mode. Connect switch or timeclock between termi-
nals 1 and 2 on terminal block 3 (sizes 034-048) or terminal
block 4 (sizes 054-104) in unit control box. See Fig. 23. The
circuit potential is 24 v.
Variable air volume units equipped with warm-up heat re-
quire that room terminals be controlled to go fully open when
unit goes into the Heating mode. Heating interlock relay (HIR)
is provided for this function. The relay is located in the unit
Proper setting of the P7 potentiometer may be made on a re-
sistance basis. The microprocessor initiates reset when it de-
tects a resistance of the thermistor plus the potentiometer of
13,084 ohm. The potentiometer set point may be calculated us-
ing the following formula:
P7R = 13,084 – T10R
Where:
P7R = the desired set point of the P7 potentiometer in ohms
T10R = the resistance of the T10 thermistor for the desired
set point
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Fig. 20 — Unit Control Box Arrangement, Sizes 034-048
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15
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034-048: TB3
054-104: TB4
034-048: TB3
054-104: TB4
OPERATING SEQUENCE — If space temperature is above
reset set point (T10 > P7), no reset will occur.
If space temperature is equal to or less that reset set point
(T10 < P7), the LED will display 20 and reset will begin.
1
2
Control will automatically adjust leaving air temperature by
the following formula:
OCCUPIED/UNOCCUPIED
SWITCH
MSP = SP + [(P3 - SP) / 3] x (P7 – T10)
where:
MSP = Modified Leaving-Air Set Point
SP = Supply-Air Set Point
NIGHT SETBACK THERMOSTAT
P3 = Maximum Supply-Air Temperature (reset limit)
P7 = Reset Initiation Temperature (reset set point)
T10 = Actual Space Temperature
NOTES:
1. Occ/Unocc switch closes when occupied.
2. Night setback thermostat closes when in night setback heating.
3
= Ratio for reset (F) (fixed parameter)
Fig. 23 — Occupied/Unoccupied Switch with
Night Setback Thermostat
Table 4 — Thermistor Resistance and Voltage
Drop Characteristics
TEMP
(F)
RESISTANCE
(Ohms)
VOLTAGE
DROP (v)
034-048: TB3
054-104: TB4
31.0
32.0
33.0
34.0
35.0
36.0
37.0
38.0
39.0
40.0
41.0
42.0
43.0
44.0
45.0
46.0
47.0
48.0
49.0
50.0
51.0
52.0
53.0
54.0
55.0
56.0
57.0
58.0
59.0
60.0
61.0
62.0
63.0
64.0
65.0
66.0
67.0
68.0
69.0
70.0
71.0
72.0
73.0
74.0
75.0
76.0
77.0
78.0
79.0
80.0
16813.8
16345.7
15892.2
15452.7
15026.7
14613.9
14213.6
13825.5
13449.2
13084.2
12730.1
12386.6
12053.3
11730.0
11416.1
11111.5
10815.8
10528.7
10250.0
9979.3
9716.5
9461.3
9213.4
8972.6
8738.6
8511.4
8290.6
8076.1
7867.7
7665.1
7468.3
7277.1
7091.2
6910.6
6735.1
6564.4
6398.6
6237.5
6080.8
5928.6
5780.6
5636.8
5497.0
5361.2
5229.1
5100.8
4976.0
4854.8
4736.9
4622.4
3.582
3.553
3.523
3.494
3.464
3.434
3.404
3.373
3.343
3.312
3.281
3.250
3.219
3.187
3.156
3.124
3.093
3.061
3.029
2.997
2.965
2.933
2.901
2.869
2.837
2.805
2.772
2.740
2.708
2.676
2.644
2.612
2.581
2.549
2.517
2.486
2.454
2.423
2.391
2.360
2.329
2.299
2.268
2.237
2.207
2.177
2.147
2.117
2.088
2.058
FIELD
SUPPLIED
3
4
7
V
POWER
SOURCE
4
6
5
N.O.
N.C.
SIGNAL
TO ROOM
TERMINALS
Fig. 24 — Heat Interlock Relay
034-048: TB3
054-104: TB4
T10
12
RESET
BOARD
P7
15
Fig. 25 — Accessory Reset Board
EXAMPLE:
T10 desired set point is 70 F.
T10R from Table 4 for 70 F is 5929 ohms.
P7R = 13,084 – 5929
P7R = 7155 ohms
Using an ohmmeter, set the P7 potentiometer to 7155 ohms
to achieve a reset initiation set point of 70 F.
Potentiometer P3 — Reset limit set point (maximum tempera-
ture value for modified supply air set point). Maximum of 70 F,
minimum 40 F. Set between leaving air set point (P1) and 70 F
(maximum range permitted by control).
17
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RED
BLK
RED
BLK
SIZES 034-048
TB3
RED
RED
BLK
RED
BLK
12
15
BLK
TO ACCESSORY SPACE
TEMPERATURE RESET
CONTROL BOARD
SIZES 054-104
TB4
12
15
SENSOR 1
SENSOR 2
SENSOR 3
SENSOR 4
SPACE TEMPERATURE RESET — 4 SENSOR AVERAGING APPLICATION
SIZES 034-048
TB3
12
RED
BLK
RED
BLK
RED
BLK
15
TO ACCESSORY SPACE
TEMPERATURE RESET
CONTROL BOARD
SENSOR 1
SENSOR 3
SENSOR 2
SIZES 054-104
TB4
12
RED
BLK
RED
BLK
15
SENSOR 4
SENSOR 5
SENSOR 6
RED
BLK
RED
BLK
NOTE: Sensor part number is HH79NZ014.
SENSOR 7
SENSOR 8
SENSOR 9
SPACE TEMPERATURE RESET — 9 SENSOR AVERAGING APPLICATION
Fig. 26 — Space Temperature Sensor Averaging
Demand Limit — The demand limit function provides a
means to limit the cooling capacity of the VAV unit using an
external discrete switch function. When enabled by the closure
of the external switch, the control will limit the available com-
pressor staging capacity according to user set points established
at demand limit potentiometer(s).
Control Module kit plus installation of 2 field-supplied control
switches (SPST-NO each). This accessory control provides for
a first step reduction of 50% to 100% of the maximum com-
pressor staging; the second step provides for reduction
between 0% and 49%. The exact percentage of capacity reduc-
tion differs depending on the number of capacity steps.
The unit controls support two types of demand limit: single-
step and 2-step control.
When demand limit is active, the LED display will show
code 22 .
SINGLE-STEP DEMAND LIMIT — This function will limit
the total compressor staging based on the ratio of the set point
potentiometer’s wiper arm position to the full scale resistance
of the potentiometer. The exact percentage of capacity reduc-
tion differs depending on the number of capacity steps.
A field-supplied potentiometer and control switch are re-
quired for this function. See installation section for specifica-
tion on potentiometer and field wiring.
INSTALLATION
Single-Step Demand Limit — A 3-wire 5 to 20 K-ohm poten-
tiometer must be field-supplied and installed. A single-
pole normally open switch is also required (field-supplied
and -installed). Locate the potentiometer (designated P4) and
the switch in a suitable location (external from the unit or in the
unit control box).
TWO-STEP DEMAND LIMIT — Two-step demand limit is
provided with the installation of the accessory Demand Limit
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Connect the potentiometer end terminals to terminals 8
and 9 on control terminal block TB3 (sizes 034-048) or TB4
(sizes 054-104) (see Fig 27). Connect the switch terminals to
the potentiometer wiper arm terminal and to terminal 10 on
TB3 or TB4.
034-048: TB3
054-104: TB4
8
To enable demand limit function, change DIP switch 5 to
position ON. (Disconnect control power before changing DIP
switch positions. Reconnect power after all changes have been
made.)
5-20K
POTENTIOMETER
(P4)
9
Set the potentiometer P4 to desired capacity reduction value.
Two-Step Demand Limit — Install the demand limit control
module (DLCM) according to the installation instructions pro-
vided with the accessory. Disconnect existing leads at connec-
tor J3 on the processor board (see instructions) and connect the
plug from the DLCM harness to connector J3.
10
SWITCH
Fig. 27 — Single-Step Demand Limit
Connect the field input control power wires (from the exter-
nal control relays) at the terminal strips marked IN1, RTN1,
IN2 and RTN2 (see Fig. 28 and 29).
To enable demand limit function, change DIP switch 5 to
position ON. (Disconnect control power before hanging DIP
switch positions. Reconnect power after all changes have been
made.)
Set the potentiometers DLCM-P1 and DLCM-P2 to desired
capacity reduction values.
Check the operation of demand limit function by using the
Quick Test procedures.
CONFIGURATION
Fig. 28 — Two-Step Demand Limit Module
Single-Step Demand Limit — Field-installed potentiometer
P4 establishes capacity reduction value for demand limit opera-
tion. Set this potentiometer between 0% and 100%. The exact
percentage of capacity reduction differs depending on the num-
ber of capacity steps.
Two-Step Demand Limit — Potentiometer P1 and P2 (locat-
ed on the accessory demand limit control module) establish the
capacity reduction values for each step of demand limit. Set po-
tentiometer DLCM-P1 between 50% and 100%. Set potenti-
ometer DLCM-P2 between 0% and 49%. The exact percentage
of capacity reduction differs depending on the number of ca-
pacity steps.
NOTES:
1. Demand limit switches are field supplied and wired.
2. Demand limit control module terminal blocks will accept up to
12-gage wire.
OPERATING SEQUENCE
Single-Step Demand Limit — If the field control switch to
the wiper arm terminal is open, all capacity stages will be avail-
able (no demand limit in effect). When the field control switch
is closed, the compressor cooling capacity is reduced by the
amount set on potentiometer P4.
3.
is field wiring.
Fig. 29 — 115-Volt Field Wiring to Accessory
2-Step Demand Limit Control Module
Control From Remote Building Management
System (BMS) — The unit control system is not a com-
municating control system, and it cannot be accessed directly
by a DDC (Direct Digital Control) control system (or by a
BACnet communication system). However, it is possible to
control some functions of these units via 4 to 20 mA or 2 to
10 vdc signals and discrete inputs (relay contact closures).
When demand limit is in effect, the LED display will show
code 22 . If a potentiometer setting or input is out of range, the
control will terminate the demand limit function and show
code 84 at the display LED.
Two-Step Demand Limit — If the field control switches are
both open (no power supplied to the Demand Limit Control
Module), all capacity stages will be available (no demand limit
in effect). When control power is supplied to terminal IN1 only
(field switch SW1 closes), the first step of the demand limit is
energized and the compressor cooling capacity is reduced by
the amount set on potentiometer DLCM-P1. When control
power is supplied to terminal IN2 (field switch SW2 closes),
the second step of the demand limit is energized and compres-
sor cooling capacity is reduced by the amount set on potenti-
ometer DLCM-P2.
Functions that can be managed from or accessed from an
external control system include:
•
•
•
•
•
•
Occupied/Unoccupied Status
Night Setback Control
Unit Supply Air Set Point Adjustment
Demand Limit (1-stage or 2-stage)
Supply Duct Pressure Set Point Adjustment
External Alarm Signal
Remote control of the economizer cycle on these units is not
recommended. Refer to the Operating Sequence section on
page 35 for a discussion on the economizer cycle operation.
When demand limit is in effect, the LED display will show
code 22 . If a potentiometer setting or input is out of range, the
control will terminate the demand limit function and show
code 84 at the display LED.
19
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OCCUPIED/UNOCCUPIED — The unit control system will
initiate normal occupied mode functions (including Morning
Warm-up, Economizer Minimum Position, and Cooling Cycle)
whenever a contact closure is made that emulates the normal
timeclock contacts. See Fig. 23. (‘‘Occupied/Unoccupied
Switch’’). The contact closure from the BMS must be an iso-
lated contact set, normally open, and suitable for 24 volts AC
pilot duty.
Configuration — Configure as follows:
1. Set DIP switch no. 2 to ON.
2. Adjust manual potentiometer to 12.6 to 12.8 k-ohm.
3. Configure transducer for job site input signal from BMS.
4. Adjust Potentiometer (P3) on the rooftop to MAXIMUM
SASP value (typically 65 to 70 F). The maximum P3 SASP
control limit is 70 F.
NIGHT SETBACK CONTROL — Night setback control is
used to control the space to a set point level that is typically
lower than during normal occupied periods (Heating Only
mode). Some applications also require a limitation on the max-
imum space temperature during unoccupied periods (Cooling
mode). Both modes are possible by closing the same contacts
used in the Occupied/Unoccupied control, or by installing a
dedicated contact set in parallel with the Occupied/ Unoccu-
pied control contacts, and using the BMS space temperature
sensing system and its logic to determine when to initiate unit
operation.
Operation — Unit will initiate SASP Reset (adjust configured
SASP upward) when the sum of the resistance (fixed resistance
+ potentiometer + transducer) exceeds 13.1 k-ohm. Once reset
is initiated, full range of reset (P3 setting minus configured
SASP) will be reached with 500-ohm increase in transducer re-
sistance (TR).
During Reset mode operation, Code 21 will appear on unit
display board.
Formula:
MSP = SASP +
Once the unit operation has been initiated by the BMS con-
tact closure, the unit operates in its normal occupied mode
manner, initiating morning warm-up if needed (as sensed by re-
turn air temperature to the unit) or cooling (controlling to cur-
rent SASP value). The Night Setback Control contacts will in-
terrupt normal unit operation when the BMS senses that space
temperatures have returned to unoccupied set point levels, and
the unit will shut down normally.
(P3 — SASP)
(3)
(0.6 F)
(100 ohm)
X
[
]
MSP: Modified SASP (SASP plus Reset)
TR: Resistance at transducer
[email protected]: TR required to reach 13.1 k-ohm start level
DEMAND LIMIT (1-STAGE OR 2-STAGE) — Both of the
Demand Limit functions on the units rely on external switches
to initiate the reset functions. Contact closures by the BMS can
be used in place of these switches. Contacts must be isolated
and suitable for 115-vac pilot duty operation.
For Single-Step Demand Limit, emulate function of switch
SW with contact closure controlled by the BMS. Set potenti-
ometer P4 manually at the unit control box. Alternatively, po-
tentiometer P4 might also be emulated by a variable resistance
transducer, with the BMS now able to adjust the amount of de-
mand limit.
For 2-Step Demand Limit, install the accessory Demand
Limit Control Module (DLCM) according the instructions on
page 18. Replace switch functions Switch 1 and Switch 2 with
contact closures controlled by the BMS (see Fig. 29).
Follow unit control configuration instructions in the De-
mand Limit section on page 18.
The contact closure from the BMS must be an isolated con-
tact set, normally open, suitable for 24 volts AC pilot duty.
NOTE: If the rooftop unit is equipped with a VFD and night
setback cooling operation is intended, the fan system must be
controlled to permit FULL SUPPLY FAN AIR DELIVERY
during unoccupied cooling operation. This is most conve-
niently attained by replicating the HIR relay function of the
rooftop unit. An HIR control sequence will force all room ter-
minals to their minimum heating CFM position, thus assuring
adequate airflow through the rooftop unit during night setback
cooling operation. During night setback cooling operation, the
return-air temperature (RAT) will be well above normal levels.
The higher RAT means that the air temperature leaving the
evaporator coil will also be well above normal levels. This sit-
uation is interpreted by the unit control system as a demand for
additional cooling stages. The unit control responds to this
demand by bringing on more stages, until typically all stages
are active. If the VFD is not working in-step with the refrigera-
tion system demand, it is possible to produce low suction pres-
sures and local frosting on the evaporator coil during the night
setback cooling operation.
UNIT SUPPLY AIR SET POINT ADJUSTMENT — The
minimum Supply Air Set Point (SASP) temperature is estab-
lished by the setting at Potentiometer P1 on the unit display
board (see Fig. 6). The control point can also be adjusted
upward by emulating the function of the accessory Space Tem-
perature Reset package. The BMS can be used to cause this
reset by adjusting the resistance value in a variable resistance
transducer with a 4 to 20 mA or 2 to 10 vdc signal generated
by the BMS.
SUPPLY DUCT PRESSURE SET POINT ADJUSTMENT
— Supply duct pressure set point adjustment from a remote
BMS is possible when the unit has been equipped with a fac-
tory-option VFD (variable frequency drive). There are two
methods available:
•
•
Direct 4 to 20 mA signal
DDC direct to the VFD
Direct 4 to 20 mA Signal — During normal unit operation,
the factory-installed VFD receives a 4 to 20 mA signal from
the Duct Pressure (DP) transducer which indicates current sup-
ply duct pressure. The VFD then determines the appropriate
fan speed (using its internal PID logic feature) and adjusts its
output to the supply fan motor to suit. It is possible to emulate
this 4 to 20 mA control signal by the BMS, which will transfer
control of the VFD to the BMS.
This emulation requires the following field-supplied parts:
•
•
Variable resistance transducer (Kele RES-1 or equiva-
lent, range 0 to 1000 ohms)
Series resistance with potentiometer, suitable for manual
adjustment to 12.5 to 13.0 k-ohms total resistance
NOTE: When providing a direct 4 to 20 mA signal to the VFD
from a BMS with DP logic, disable the PID (proportion inte-
grated derivative calculation process) feature of the VFD.
DDC Direct to the VFD — Several accessory interface
boards are available for the VFDs that permit direct communi-
cation between the VFD and several BMS communication sys-
tems. Contact your Carrier representative for information on
selecting an appropriate accessory interface board and the
name of the local service office (for sale and installation of the
accessory boards).
Field Connections (see Fig. 30) — Connect fixed resistance
with manual potentiometer and variable resistance transducer
in series.
Connect wiring to rooftop unit at:
Size 034-044: TB3-12 and TB3-15
Size 054-104: TB4-12 and TB4-15
20
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034-048: TB3
054-104: TB4
EXTERNAL ALARM SIGNAL — The unit controls provide
an external alarm status signal via a 115-vac output signal at
the relay board J5, available at TB2-4 and TB2-5 (common).
This signal can be forwarded to the BMS by adding a signal
relay at the alarm output, placing its coil across terminals TB2-
4 and TB2-5 and using its contacts to control a discrete input to
the BMS (see Fig. 31).
TRANSDUCER
BMS
P
CONTROL
R
12
(4 TO 20 MA
OR
2 TO 10 VDC
SIGNAL)
15
The alarm signal output is energized when any of the diag-
nostic codes is tripped.
REMOTE ECONOMIZER CONTROL — Economizer con-
trol is tightly integrated into the unit’s capacity control algo-
rithms and diagnostic routines. Consequently, control
modifications that interfere with this standard operating
sequence are not recommended.
LEGEND
P
R
—
—
Manual Potentiometer
Fixed Resistor
Field Wiring
Fig. 30 — Remote SASP Wiring
Economizer position is determined by the unit processor
board based on current outdoor air enthalpy status and cooling
capacity demand. The economizer damper actuator is a floating
point device with an internal brake and spring return. Its posi-
tion is determined by the sequencing of relays EOR (Econo-
mizer Open Relay) and ECR (Economizer Close Relay). The
economizer’s current position is sensed by the processor board
through position feedback potentiometer P2.
TB2
4
TB2
5
LIGHT
R
Whenever the economizer position potentiometer signal is
not consistent with the processor board’s commanded position,
a fault condition is determined by the processor board and an
alarm signal is initiated. The processor board also attempts to
return the economizer damper to its fully closed position dur-
ing this fault condition by energizing the ECR relay.
RELAY
Any attempt to effect an external control of the economizer
actuator will lead to an alarm condition and an automatic re-
sponse by the unit control to attempt to close the dampers.
SIGNAL TO BMS
Smoke Control Modes — It is common practice to use
rooftop units for aid in building smoke control in the event of a
building fire. The available functions include: Fire Shutdown,
Pressurization, Evacuation, and Smoke Purge. These functions
are enhanced when multiple rooftop units are used to zone a
building.
Implementation of the various Smoke Control modes on
these units requires the installer to modify the unit wiring to
add contacts (via either manual switches or relays) that will se-
lectively interrupt and override standard factory control se-
quences. See Table 5.
Smoke control mode Pressurization requires the economiz-
er function. Evacuation and Smoke Purge modes require both
economizer and power exhaust functions. Both functions are
standard features on 48FM and 50FM,FS units. These func-
tions require factory-installed options, field-installed accesso-
ries and/or field-supplied exhaust systems on 48FK,JK and
50FK,FY,JK,JY units. Consult price pages for specific details.
FIRE SHUTDOWN MODE — Fire Shutdown mode termi-
nates all unit operation (cooling, heating, supply fan and power
exhaust). This mode prevents recirculation of contaminated air
back into the space or the admission into the space of unsuit-
able outside air.
LEGEND
R
—
Fixed Resistor
Factory Wiring
Field Wiring
Fig. 31 — External Alarm Indication
•
running the supply fan (optional inlet guide vanes open
or optional VFD [variable frequency drive] at normal
duct static pressure set point)
shutting off the power exhaust fans (Standard on 48FM
and 50FM,FS units. Factory-installed option or field-
installed accessory on 48FK,JK and 50FK,JK units)
•
This allows the space to be overpressurized relative to adja-
cent zones and prevents or slows entry of smoke into this space
from adjacent zones.
EVACUATION MODE — Evacuation mode removes smoke
or undesirable air from interior spaces without reintroducing
unsuitable air. The economizer and power exhaust are required
for this function. The economizer and power exhaust are
standard on 48FM and 50FM,FS units. The economizer is a
factory-installed option and the power exhaust is a factory-
installed option or field-installed accessory on 48FK,JK and
50FK,JK units. Evacuation is accomplished by:
•
•
•
•
turning supply fan off
PRESSURIZATION MODE — Pressurization mode is
intended to keep smoke out of a zone. The economizer is
required for this function. The economizer is standard on
48FM and 50FM,FS units. The economizer is a factory-
installed option on 48FK,JK and 50FK,FY,JK,JY units. Pres-
surization is accomplished by:
opening the economizer
running the exhaust fans
opening the exhaust dampers
•
opening the economizer
21
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SMOKE PURGE MODE — Smoke Purge mode removes
smoke from the interior spaces and replaces it with fresh out-
side air. The economizer and power exhaust are required for
this function. The economizer and power exhaust are standard
on 48FM and 50FM,FS units. The economizer is a factory-
installed option and the power exhaust is a factory-installed
option or field-installed accessory on 48FK,JK and 50FK,JK
units. Smoke purge is accomplished by:
CONFIGURATION — No set points required for Smoke Con-
trol modes. Modes are activated by energizing all switches
appropriate for each Smoke Control mode.
OPERATING SEQUENCE
Fire Shutdown — At command from the field switches (see
Table 5), all unit operation (cooling, heating, supply fan and
power exhaust) will terminate.
Pressurization — At command from the field switches for
Pressurization mode (see Table 5):
1. Economizer dampers will open.
2. The HIR function will energize, opening room terminals
to full-open (heating) positions.
3. Supply fan will run. (If equipped with IGV: control vanes
will open. If equipped with VFD: the VFD will control to
duct static set point or best available with all terminals
open.)
•
•
•
•
turning supply fan on
opening the economizer
running the exhaust fans
opening the exhaust dampers
INSTALLATION — To enable one or more of the possible
smoke control modes available with these units, determine the
switches required for the desired mode(s) from Table 6, field-
supply and install the appropriate switches and field wire per
Fig. 32. Switch functions are shown in Table 7.
4. Power exhaust dampers (if equipped) will close.
5. Power exhaust fans (if equipped) will turn off.
Table 5 — Smoke Control Modes
Evacuation — At command from the field switches for Evacu-
ation mode (see Table 5):
1. Supply fan will turn off.
2. Economizer dampers will open.
3. Exhaust fans will run at maximum capacity.
4. Exhaust dampers will open.
Smoke Purge — At command from the field switches for
Smoke Purge mode (see Table 5):
MODE
FUNCTION
Fire
Pressur-
ization
Smoke
Purge*
On
Open/On
Open
Evacuation*
Shutdown
Supply Fan
IGV/VFD†
Economizer
Return Air
Damper
Exhaust
Fans
Off
—
Closed
On
Off
—
Open
Open/On
Open
Open
Off
Closed
Off
Closed
On
Closed
On
1. Economizer dampers will open.
2. The HIR function will energize, opening room terminals
to full-open (heating) positions.
Exhaust
Damper
Closed
Closed
Open
Open
LEGEND
3. Supply fan will run. (If equipped with IGV: Control vanes
will open. If equipped with VFD: the VFD will control to
duct static set point or best available with all terminals
open.)
4. Exhaust fans will run at maximum capacity.
5. Exhaust dampers will open.
IGV — Inlet Guide Vane
VAV — Variable Air Volume
VFD — Variable Frequency Drive
*Power exhaust function required for this mode.
†Applicable to VAV units with appropriate options.
Table 6 — Smoke Control Switches Required for Each Mode
EVACUATION
(Modulating Power
Exhaust)
FIRE
SHUTDOWN
SMOKE
PURGE
PRESSURIZATION
SW-1
SW-2
SW-1
SW-2
SW-4
SW-5
SW-6
SW-1
SW-2
SW-3
SW-5
SW-6
SW-7
SW-8*
SW-1
SW-2
SW-3
SW-4
SW-9A/B
SW-9A/B
*Not required on 48FM and 50FM,FS units (high capacity power exhaust units).
NOTE: All switches are shown in “as installed” (power OFF or deenergized) position. In these
positions, none of these modes will be activated; normal unit operation is permitted by the base
unit controls. To initiate any mode, all switches listed under this mode in the table must be ener-
gized, causing the depicted contact position to change from depicted positions to energized posi-
tions. Switches may be manually or electrically operated.
22
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Table 7 — Switch Functions
SWITCH
NUMBER
CONFIGURATION
VOLTAGE
FUNCTION
SW-1
SW-2
SW-3
SW-4
SW-5
SW-6
N.C.
N.C.
N.O.
N.O.
N.C.
N.O.
115
115
24
115
115
115
Deenergize 115-v (OFC, Comp, IFC, Electric Heaters)
Deenergize TRAN7 (Process Board)
Energize EOR (Open Economizer Outside Air Dampers)
Energize IFC and CR-3 (IGV/VFD)
Isolate IFC and PEC for Separate Operation
Energize PEC (Power Exhaust)
Open PED at DPS (48FK,JK and 50FK,JK Units) Force Power Exhaust VFD
to Maximum Speed (48FM and 50FM,FS Units)
Block Auto-Close at DPS (Due to Low BP)
SW-7
SW-8*
N.O.
N.C.
24
24
A: N.O.
B: N.C.
SW-9A/B
115 max
Signal Room Terminals to Open (HIR1)
*Not required on 48FM and 50FM,FS units (units with high capacity power exhaust).
LEGEND
BP — Building Pressure
DPS — Differential Pressure Switch
EOR — Economizer Open Relay
HIR — Heat Interlock Relay
IFC — Indoor Fan Contactor
IGV — Inlet Guide Vane
N.C. — Normally Closed
N.O. — Normally Open
PEC — Power Exhaust Contactor
PED — Power Exhaust Damper
OFC — Outdoor Fan Contactor
VFD — Variable Frequency Drive
INLET GUIDE VANES — The tubing for the duct pressure
Air Pressure Tubing — Before options such as inlet
guide vanes (IGV), variable frequency drive (VFD), and/or
modulating power exhaust can operate properly, the pneumatic
tubing for pressure sensing must be installed. Use fire-retardant
plenum tubing (field-supplied). Tubing size depends on type of
control device (see Table 8 below). Tubing must be run from
the appropriate sensing location (in the duct or in the building
space) to the control device location in the unit.
(DP) control option should sample supply duct pressure about
2/3 of the way out from the unit in the main trunk duct, at a
location where a constant duct pressure is desired.
The inlet guide vanes are controlled by a differential pres-
sure switch (DPS). On sizes 034-048, the DPS is located in the
auxiliary control box at the economizer end of the unit (see
Fig. 33). On sizes 054-104, the DPS is located in the supply fan
section. See Fig. 34. Use a nominal 3/8-in. plastic tubing.
SUPPLY FAN VARIABLE FREQUENCY DRIVE — The
tubing for the duct pressure (DP) control option should sample
supply duct pressure about 2/3 of the way out from the unit in
the main trunk duct, at a location where a constant duct pres-
sure is desired.
Table 8 — Tubing Size
NOMINAL TUBE
OPTION
UNITS
ALL
SIZE (in.)
3
Inlet Guide Vanes (IGV)
/
8
The duct pressure is sensed by a pressure transducer. The
pressure transducer output is directed to the VFD. On 034-048
units the DP transducer is located in the auxiliary control box.
On 054-104 units, the DP transducer is located in the supply
fan section. See Fig. 34. Use a nominal 1/4-in. plastic tubing.
Supply Fan Variable
1
ALL
/
4
Frequency Drive (VFD)
3
FK,FKX,JK,JKX
FM,FS
/
/
8
Modulating Power Exhaust
1
4
23
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054-104 UNITS
034-048 UNITS
TB2
5
SW-1
TB2
6
TB2
13
SW-1
TB2
14
REMOVE JUMPER
REMOVE JUMPER
TB2
1
SW-2
TB2
2
TB2
7
SW-2
TB2
8
REMOVE JUMPER
REMOVE JUMPER
SW-3
SW-4
TB3
5
TB3
1
SW-3
SW-4
TB4
5
TB4
1
TB2
9
TB2
5
TB2
2
TB2
13
TB2
8
SW-5
TB2
9
TB2
1
SW-5
TB2
2
REMOVE JUMPER
REMOVE JUMPER
TB2
8
TB2
5
SW-6
TB2
1
TB2
13
SW-6
SW-9A
TB3
4
TB3
3
SW-9A
TB4
4
TB4
3
HIR
HIR
TB4
7
TB3
3
SW-9B
TB3
7
TB4
3
SW-9B
4
4
5
5
REMOVED FROM TB3-7
REMOVED FROM TB4-7
48FK, JK AND 50FK, JK034-104 UNITS
SW-7
DPS
NC
SW-8
WHT
C
VIO
NO
REMOVED
FROM C-DPS
GRA
48FM, AND 50FM, FS034-104 UNITS
SW7
PEVFD
CC
PEVFD
S1
LEGEND
DPS
HIR
— Differential Pressure Switch
— Heat Interlock Relay
PEVFD — Power Exhaust Variable Frequency Drive
SW
TB
— Switch
— Terminal Block
Fig. 32 — Smoke Control Wiring
24
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MODULATING POWER EXHAUST
48FK,JK and 50FK, JK Units — The tubing for the building
pressure control (achieved via the Modulating Power Exhaust
option/accessory) should sample building pressure in the area
near the entrance lobby (or other appropriate and sensitive
location) so that location is controlled as closely to design pres-
sures as possible.
A differential pressure switch (DPS) is used to control the
actuator on the modulating discharge damper in exhaust fan
no. 1. The building pressure (BP) DPS is located in the auxilia-
ry control box of the unit. See Fig. 33 and 35. Use a nominal
3/8-in. plastic tubing.
For instructions on adjusting BP control set points, refer to
Start-Up, Modulating Power Exhaust section in this book.
48FM and 50FM,FS Units — The tubing for the building
pressure control (achieved through the High Capacity Modu-
lating Power Exhaust) should sample the building pressure in
the area near the entrance lobby (or other appropriate and sen-
sitive location) so that the location is controlled as closely to
design pressures as possible.
Fig. 33 — Modulating Power Exhaust and Inlet
Guide Vane Differential Pressure Switch
(Sizes 034-048)
A building pressure transducer (BPT) is used to sense the
building pressure and supply a 4 to 20 mA signal to the power
exhaust VFD (PE VFD) which controls the speed of exhaust
fan motor no. 1 and stages on/off power exhaust fan motor
no. 2 to maintain the building pressure. The BPT is located in
the auxiliary control box. Use a nominal 1/4-in. plastic tubing.
For instructions on adjusting the BP control set point, refer
to Start-Up, High Capacity Modulating Power Exhaust section
in this book.
START-UP
Initial Check
IMPORTANT: Do not attempt to start unit, even
momentarily, until all items on the Controls Start-Up
Checklist (in installation instructions) and the following
steps have been completed.
Fig. 34 — Inlet Guide Vane Differential
Pressure Switch and Variable Frequency Drive
(Sizes 054-104)
1. Verify unit has been installed per the Installation Instruc-
tions included in the unit installation packet.
2. Verify that all auxiliary components (sensors, controls,
etc.) have been installed and wired to the unit control
boxes per these instructions, the unit Installation Instruc-
tions, and the unit wiring label diagrams.
3. Verify that air pressure hoses (static, duct, etc.) are prop-
erly attached, routed, and free from pinches or crimps that
may affect proper control operation.
4. Set any control configurations that are required (field-
installed accessories, etc.). The unit is factory configured
for all appropriate factory-installed options with the ap-
plicable controls programmed to the default values.
5. Check and adjust unit set points. See Table 9.
6. Check tightness of all electrical connections.
Fig. 35 — Modulating Power Exhaust Differential
Pressure Switch (Sizes 054-104)
7. Perform quick test (see Quick Test Program section on
page 31).
25
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Table 9 — Potentiometer Inputs and Ranges
CONTROL
POTENTIOMETER
DESCRIPTION
LOCATION
VALID
DEFAULT VALUE
45 F if -22 F < P1 < 45 F
RANGE
Supply Air
Set Point
Economizer
Position
Display
Board
Economizer
Motor
Accessory
Board
P1
P2*
P3
45 to 70 F
0 to 100%
0 to 80 F
70 F if P1 > 70 F OR IF P1 < -22 F
None (0 if P2 is bad)
Reset Limit
None (limited to 70 F maximum)
None
Demand Limit,
Single-Step
P4†
Main Control Box
0 to 100%
DLCM-P1
DLCM-P2
DLCM Board
DLCM Board
50 to 100%
0 to 49%
None
None
Demand Limit,
2-Step
Minimum Economizer
Position
P5*
Accessory Board
Accessory Board
Reset Board
0 to 100%
40 to 80 F
40 to 100 F
None
40 F if 0° F < P6 < 40 F OR IF P6 < 95 F
OR IF P6 < 0
80 F if 80 F < P6 < 95 F
Warm-Up
Set Point
P6
Reset
Temperature
P7**
None
*Optional factory-installed economizer is required. Potentiometer P2 is not a set point.
†Accessory two-step demand limit module is required (which has 2 potentiometers), or a 5 to 20 k-ohm
field-supplied potentiometer is required for single-step demand limit.
**Accessory temperature reset is required.
NOTE: Potentiometers P1-P6 input data to pin terminal connector J3.
Potentiometer P7 inputs data to pin terminal connector J1.
Configuration Header — The configuration header is a
Table 11 — Configuration Header Jumpers
series of 8 small wires that are broken (open circuit) or unbro-
ken (closed circuit) in a pattern to indicate several unique char-
acteristics of the unit. The configuration header is factory set
and should not be changed; changing the factory setting may
cause the unit to malfunction.
JUMPER
NUMBER
FACTORY
SETTING
FUNCTION
Unit Type
MEANING
1,2
3,4,5
6
I
I
VAV Rooftop Unit
2 Compressors
TXV
Qty Compressors
Expansion Valve
Power Frequency
Not Used
I
Before start-up, visually check the configuration header
against the factory setting for the unit size. See Table 10 for
factory settings. See Table 11 for purpose for each jumper.
7
8
60 Hz
I
No Significance
LEGEND
Thermostatic Expansion Valve
Table 10 — Configuration Header and
DIP Switch Factory Settings
TXV
—
VAV — Variable-Air Volume
—
—
Broken Jumper (open circuit)
Unbroken Jumper (closed circuit)
I
UNIT SIZES
034-038,
048-088
UNIT SIZE
044
UNIT SIZE
104
JUMPER OR
SWITCH NO.
Header Switch Header Switch Header Switch
Position Position Position Position Position Position
DIP Switches — The DIP switches configure the unit for
several factory-installed options and field-installed accessories,
plus factory unloaders. The DIP switches are located under a
plastic enclosure which must be removed for access. See
Fig. 1. The switches can be field adjusted. Switches must only
be adjusted when control power is deenergized. See Table 12
for DIP switch purposes and Table 10 for factory settings of the
switch positions.
1
2
3
4
5
6
7
8
Off
Off
Off
Off
Off
Off
I
I
I
I
I
I
I
On/Off*
On/Off*
Off
On/Off*
On/Off*
Off
On/Off*
On/Off*
Off
I
Off
I
I
On
I
I
On
On
Off
Off
I
Off
Off
Off
LEGEND
DIP
—
—
—
Dual, In-Line Package
Disconnect control power before changing the settings of
the DIP switches. To disconnect control power, open the
control circuit breaker.
Broken Jumper (open circuit)
I
Unbroken Jumper (closed circuit)
*Depending on factory-installed options or field-installed accessories.
26
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DIP SWITCH NO. 1 — Supply Air Set Point (SASP) Reset
Type. Factory setting is OFF. Do not change.
DIP SWITCH NO. 2 — SASP Reset Enabled. Factory setting
is OFF (no SASP reset enabled). If SASP reset has been
installed, enable it by changing switch position to ON.
DIP SWITCH NO. 3 — Economizer option. If economizer
option has been installed, this switch will be ON. If there is no
economizer installed, this switch will be OFF. For all 48FM
and 50FM,FS units, this switch will be ON. Confirm setting
per Table 10. Change only if in error.
DIP SWITCH NO. 4 — Morning Warm-Up. For 48FK,FM,JK
units, this switch will be ON (morning warm-up enabled). For
50FK,JK units with factory-installed electric heaters, this
switch will be ON. For all other units, this switch will be OFF.
If accessory electric heaters are installed (for 50FK,JK 034-
074 units without plenum option), change this switch to ON.
Potentiometer inputs and ranges are summarized in Table 9.
Information on individual set point potentiometers (including
function, location and range data) are shown below:
SUPPLY AIR SET POINT (Leaving-Air Temperature) (P1)
— This potentiometer establishes the set point for cooling
cycle operation of the VAV unit. The VAV control uses a valid
control range of 45 to 70 F, and the potentiometer has a valid
range of –22 to 70 F. If the set point is between –22 and 45 F,
the control will use a value of 45 F. If the set point is outside
the valid range (less than –22 F or greater than 70 F), an alarm
condition will be signaled and a default value of 70 F will be
used.
ECONOMIZER MINIMUM POSITION (P5) — This potenti-
ometer specifies the minimum opening position for the
optional economizer during running periods. It has both a valid
range and an operational range of 0 to 100%.
SASP RESET TEMPERATURE (P7) — This potentiometer
establishes the space temperature at which the control will ini-
tiate the reset of the SASP (i.e., the unit control begins to raise
the base SASP, to prevent overcooling of the space). The
potentiometer has a valid range of 40 to 100 F. Refer to Space
Temperature Reset section on page 13 for further discussion of
SASP Reset operation.
DIP SWITCH NO. 5 — Demand Limit. Factory setting is OFF
(demand limit not enabled). If Demand Limit (single-step or
2-step accessory) has been installed, change this switch to ON.
DIP SWITCHES NO. 6 AND NO. 7 — Unloader Configu-
ration. These are factory set to match unit size. Confirm set-
tings per Table 12. Change only if in error.
Table 12 — DIP Switches
RESET LIMIT (P3) — Used in conjunction with P7 potenti-
ometer, this potentiometer establishes the maximum tempera-
ture for the modified SASP value during the Reset function.
This potentiometer has a valid range of 0° to 80 F.
DEMAND LIMIT, SINGLE-STEP (P4) — This potentiome-
ter establishes the maximum amount of compressor capacity
permitted by the unit control when single-step demand limit
operation is implemented (by closing contact set to potentiom-
eter wiper arm). This potentiometer is field-supplied and
-installed and will be located in the main control box. The
valid range is 0% to 100%, which is also the operational range.
SWITCH
NO.
SWITCH
POSITION*
FUNCTION
MEANING
Reset
Mode
Space or Outdoor-Air Reset
(DO NOT CHANGE)
1
2
3
4
5
Off
Reset
Select
On
Off
Reset Used
Reset Not Used
On
Off
Enable Economizer
Disable Economizer†
Economizer
Morning
Warm-Up
On
Off
Enable Morning Warm-Up**
Disable Morning Warm-Up**
Demand
Limit
On
Off
Enable Demand Limit
Disable Demand Limit
If the wiper arm is open, all capacity stages can be used.
When the wiper arm is closed, the capacity is reduced by the
amount set on potentiometer P4.
Off, Off
On, Off
Off, On
No Unloaders
1 Unloader
6,7
8
Unloaders
Not Used
2 Unloaders
Off
No Significance
DEMAND LIMIT, 2-STEP — The accessory 2-step demand
limit control is a 2-potentiometer system. The demand limit
control board (DLCM) accessory board is field-installed in the
main control box; the 2 control potentiometers are located on
the DLCM. Potentiometer DLCM-P1 establishes the maxi-
mum amount of compressor capacity available when SW1 is
closed and has a valid range is 50% to 100%. Potentiometer
DLCM-P2 establishes the maximum amount of compressor
capacity available when SW2 is closed and has a valid range is
0% to 49%.
If no power is supplied to the DLCM, all capacity stages
can be used. When power is supplied to terminal IN1 only, the
first step of demand limit control is energized and the capacity
is reduced by the amount set on potentiometer P1. When power
is supplied to IN2 (or IN1 and IN2), the capacity is reduced by
the amount set on potentiometer P2.
MORNING WARM-UP (P6) — This potentiometer estab-
lishes the set point temperature for the Morning Warm-Up
function. This is the temperature at which the morning warm-
up sequence is terminated and VAV cooling operation begins.
The valid control range is 0° to 95 F, but the control is pro-
grammed to accept a range of 40 to 80 F. If the set point is
between 0° and 40 F, the control will use a value of 40 F. If the
set point is between 80 and 95 F, the control will use a value of
80 F. If the set point is outside the valid range (less than 0° F or
greater than 95 F, an alarm condition will be signaled and a
default value of 40 F will be used.
LEGEND
— Dual, In-Line Package
DIP
*Control circuit breaker must be off before changing the setting of the DIP
switch.
†No economizer.
**And/or electric heat (50FK,JK034-074 units without plenum only).
Adjusting Set Points — Set points for unit operation
are established via potentiometer settings. Set points for Supply
Fan controls are set at the VFD keypad (if installed) or at the
IGV differential pressure switch (DPS1) (if IGV option in-
stalled). Set points for modulating power exhaust (option or ac-
cessory) are set at the differential pressure switch (DPS2).
Set points for high capacity modulating power exhaust
(48FM and 50FM,FS units) are set at the power exhaust VFD
keypad.
Potentiometers — All of the set point potentiometers
must be set before the unit is started in order for the unit to
function properly. Each of the potentiometers has a valid range
that is used by the control. The valid range is defined as the po-
tentiometer’s resistance value that the control will not consider
to be in error. This is usually between 10% and 90% of the po-
tentiometer’s total resistance. The control has been pro-
grammed to accept an operational range for the potentiometer,
which may not be the same as the valid range.
27
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Supply Fan Control with IGV Option — The inlet
guide vane option will modulate the supply fan airflow in order
to maintain the static pressure in the supply duct. The set point
for duct static pressure is established at the differential pressure
switch for the IGV control.
SIZE 034-048 UNITS — The inlet guide vane differential
pressure switch is located in the auxiliary control box mounted
in the corner under the side air hood that is next to the access
door marked FILTER SECTION. To gain access to this control
box, remove the auxiliary control box cover. When replacing
cover, be sure to properly secure it in order to prevent water
from being drawn into the unit. See Fig. 36 and 37.
SIZE 054-104 UNITS — The inlet guide vane differential
pressure witch is mounted on an upright located behind the
supply-fan motor. See Fig. 36-38.
The IGV differential pressure switch has an adjustable set
point range of 1.1 to 3.5 in. wg. and a factory setting of
1.9 in. wg.
*The inlet guide vane differential pressure switch for the 034-048
units is located in the back of the unit in the auxiliary control box. Its
location is not shown in this figure.
To adjust set point, turn set point adjusting screw (see
Fig. 39) clockwise to decrease set point and counterclockwise
to increase set point. This switch also has an adjustable null
span. The null span is the pressure change that can be made
without contacts opening or closing. It is adjustable from
0.06 in. wg to 0.17 in. wg when set point is at minimum posi-
tion (1.1 in. wg) and 0.11 in. wg to 0.31 in. wg when set point is
at maximum position (3.5 in. wg). To adjust null span, turn a
null adjusting screw (Fig. 39) clockwise to decrease span and
counterclockwise to increase span. All switches leave factory
with null span set at maximum position. The smaller the null
span, the closer the pressure will be maintained to desired set
point.
Fig. 36 — Inlet Guide Vane Motor,
50FK,JK034-074 Units
Supply Fan Control with VFD Option — The VFD
option will modulate Supply Fan motor (and thus wheel) speed
to maintain the static pressure in the ductwork. Set point for the
VFD option is set at the VFD, using the display keyboard on
the front of the VFD enclosure. See Fig. 40.
NOTE: The VFD will always provide the proper phase
sequence to the supply-fan motor. The supply-fan motor oper-
ates in proper rotation regardless of the phase sequence to the
unit. If, upon start-up, the outdoor fans operate backwards but
the supply fan operates in the correct direction, reverse any two
leads to the main terminal block. All fans will then operate in
the correct direction.
*The inlet guide vane differential pressure switch for the 034-048
units is located in the back of the unit in the auxiliary control box. Its
location is not shown in this figure.
Fig. 37 — Inlet Guide Vane Motor, 48FK,JK, 50FJ,JY,
and 50FJX,FJY,FKX,FKY034-074 Units
The supply duct pressure transducer has a range of 0.0 to
5.0 in. wg. Its output is a 4 to 20 mA signal, scaled to this
range. The VFD translates this 4 to 20 mA input signal to rep-
resent a frequency value over the control range of 0 to 60 Hz.
The factory default set point is 30 Hz, representing a supply
duct pressure of 2.5 in. wg.
Factory-installed optional VFD is located near the supply
fan and motor. During any service work or programming at
the VFD, operation of the fan and motor is not desirable
and may be dangerous. Either disable the unit supply fan
(following instructions below) or install the accessory VFD
remote display accessory.
Fig. 38 — Inlet Guide Vane Motor,
Size 078-104 Units
28
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DISABLE SUPPLY FAN MOTOR — To disable the supply
fan motor and change programming of VFD set point:
CAPACITOR
1. Turn off Indoor Fan Circuit Breaker (IFCB). This will re-
move power to the VFD.
NULL
ADJUSTMENT
COM
N.C.
N.O.
Ensure the “CHARGE” lamp on the VFD is unlit. This
may take up to 4 minutes. The “CHARGE” lamp indicates
that the main capacitors in the VFD are charged. Internal
components of the VFD should not be touched until the
“CHARGE” lamp is completely out. Electrical shock can
cause injury or death.
SET
2. Wait for the VFD display to go blank and remove VFD
cover without touching any interior components.
POINT
ADJUSTMENT
3. Ensure that the charge indicator lamp is out which indi-
cates that the VFD is discharged. The lamp is located on
the upper right hand corner of the terminal block. If still
lit, wait until lamp goes completely out. This may take
several minutes.
4. Remove jumper from terminals ST-CC (see Fig. 41) and
replace VFD cover.
5. Turn on IFCB.
6. The drive output will now be disabled but the program-
ming can be changed.
SET
POINT
INDICATOR
LEGEND
COM — Common
N.C. — Normally Closed
N.O. — Normally Open
Fig. 39 — Differential Pressure Switch for Inlet
Guide Vane and Static Pressure Control Option
and Modulating Power Exhaust Option
7. Change VFD set point according to Table 14 shown
on page 30.
HZ
8. Once the program changes are completed, turn off IFCB.
PERCENT
SECONDS
KW/AMPS/VOLTS
9. Wait for the VFD display to go blank and remove VFD
cover without touching any interior components.
10. Ensure that the charge indicator lamp is out which indi-
cates that the VFD is discharged. The lamp is located on
the upper right hand corner of the terminal block. If still
lit, wait until lamp goes completely out. This may take
several minutes.
SETUP
PROGRAM
RUN
MONITOR
11. Replace jumper to terminals ST-CC.
12. Replace VFD cover.
13. Turn on IFCB to enable the drive.
STOP
READ
For additional information on the VFD (including basic
troubleshooting, factory jumper arrangements, and Carrier fac-
tory defaults programming), refer to Troubleshooting, Supply
Fan Variable Frequency Drive section (page 52).
WRITE
RESET
LOCAL/REMOTE
MANUAL/AUTO
IMPORTANT: The Carrier factory default values for the
VFD may be different than the default values of the
manufacturer. Refer to the Service section when check-
ing default values.
SPEED CTRL
RUN MODE
Fig. 40 — Variable Frequency Drive Keypad
P24 RES RR
F
R
S1 S2 S3 S4 RCH P24 LOW LOW
CC RX PP IV FP FLC FLB FLA
DETERMINE VFD SET POINT — The unit of measure for
the Duct Pressure set point at the VFD is output frequency
(Hz), corresponding to the desired DP set point (DPSP) in
inches of water gage (in. wg). To convert desired DPSP into
the VFD set point, refer to Table 13. Locate the pressure value
in the table closest to the desired DPSP for this installation
and use the corresponding VFD set point (Hz) value. If neces-
sary, interpolation between duct static pressure values is
permissible.
ST
FM AM CC
REMOVE
JUMPER
Fig. 41 — Jumper Removal to Disable Motor
ADJUST VFD SET POINT — To adjust the VFD set point,
the VFD must be powered; however, since it is located near the
supply fan and motor, operation of the fan and motor is not
desirable. Either disable the Supply Fan or install the accessory
VFD remote display accessory.
29
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Table 13 — VFD Set Point (Frequency Command) for Duct Pressure
PRESSURE
(in. wg)
CONTROL SIGNAL
(mA)
PRESSURE
(in. wg)
VFD SET POINT
(Hz)
CONTROL SIGNAL
(mA)
VFD SET POINT (Hz)
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
0
3
6
4.0
4.8
5.6
6.4
7.2
8.0
8.8
9.6
2.00
2.25
2.50
2.75
3.00
3.25
3.50
24
27
30
33
36
39
42
10.4
11.2
12.0
12.8
13.6
14.4
15.2
9
12
15
18
21
Table 14 — Changing the VFD Set Point (Frequency Command)*
KEY OPERATION
LED MESSAGE
EXPLANATION
Standard Monitor Mode (output frequency). If drive is disabled, display
will read “OFF”. If enabled, display will show current output frequency
XX.X or OFF
↓
↓↑
60.0
45.0 (flashing)
Pressing arrow key once will display the current frequency set point
Pressing up/down arrow keys changes the desired set point
When the Read/Write key is pressed, the parameter name (FC) and the new value (45.0)
FC and 45.0 (flashing) will alternately flash to indicate that the new value has been stored. After 2 cycles, the display will
return to the standard monitor mode.
READ
WRITE
Standard Monitor Mode (output frequency). If drive is disabled, display
will read “OFF”. If enabled, display will show current output frequency
XX.X or OFF
*Choose set point from Table 13 according to desired duct pressure or Table 15 according to desired building pressure.
power exhaust fan motor no. 2 to maintain the building pres-
Modulating Power Exhaust (Option or Acces-
sory) (48FK,JK and 50FK,JK Units) — The Mod-
ulating Power Exhaust system will maintain space pressure by
modulating power exhaust fan no. 1 and staging power exhaust
fan no. 2. Building pressure set point is established at the mod-
ulating power exhaust differential pressure switch (DPS).
sure. The set point for the building pressure control is set at the
power exhaust VFD using the keyboard on the front of the
power exhaust VFD enclosure. See Fig. 40.
NOTE: The VFD will always provide the proper phase
sequences to the power exhaust fan motor.
SIZE 034-048 UNITS — The modulating power exhaust dif-
ferential pressure switch is located in the auxiliary control box
mounted in the corner next to the power exhaust motor door.
To gain access to this control box, remove the auxiliary control
box cover. When replacing cover, be sure to properly secure it
in order to prevent water from being drawn into the unit. See
Fig. 33.
SIZE 054-104 UNITS — The modulating power exhaust dif-
ferential pressure switch is mounted below the auxiliary con-
trol box next to the access door labeled FILTER SECTION.
See Fig. 35.
DIFFERENTIAL PRESSURE SWITCH — The modulating
power exhaust DPS has a set point range of 0.5 in. wg to
–0.5 in. wg. Factory setting is +0.1 in. wg. To adjust set point,
turn set point adjusting screw (see Fig. 39) clockwise to
decrease set point and counterclockwise to increase set point.
This switch also has an adjustable null span. The null span is
the pressure change that can be made without contacts opening
or closing. It is adjustable from 0.06 in. wg to 0.14 in. wg when
set point is at minimum position (–0.5 in. wg) and 0.07 in. wg
to 0.14 in. wg when set point is at maximum position
(+0.5 in. wg). To adjust null span, turn null adjusting screw
(Fig. 39) clockwise to decrease span and counterclockwise to
increase span. All switches leave factory with null span set at
maximum position. The smaller the null span, the closer the
pressure will be maintained to desired set point.
The exhaust fan motor operates in proper rotation regardless
of the phase sequence to the unit. If, upon start-up, the outdoor
fans operate backwards but the exhaust fan operates in the cor-
rect direction, reverse any two leads on the main terminal
block. All fans will then operates in the correct direction.
The building pressure transducer has a range of –0.5 to
+0.5 in. wg. The output is a 4 to 20 mA signal, scaled to this
range. The VFD translates the 4 to 20 mA signal to represent a
frequency value over the control range of 0 to 60 Hz. See
Table 15. The set point for duct pressure control is established
at the power exhaust VFD keypad in terms of Hz. The factory
default set point is 30 Hz, representing a building pressure of
0.0 in. wg.
DETERMINE POWER EXHAUST VFD SET POINT —
The unit of measure for the building pressure set point (BPSP)
at the power exhaust VFD is output frequency (Hz), represent-
ing the desired BPSP (in. wg). To convert the desired BPSP
into the power exhaust VFD set point, refer to Table 15. Locate
the pressure value in the table closet to the desired BPSP for
the application and use the corresponding set point (Hz) value.
If necessary, interpolation between duct static pressure values
is permissible.
ADJUST PE VFD SET POINT — To adjust the PE VFD set
point, the PE VFD must be powered. Since it is located in the
indoor section of the unit, use caution to ensure that the service
access door is blocked open and will not close suddenly.
High Capacity Power Exhaust (48FM and
50FM,FS Units) — The power exhaust VFD will modu-
late the power exhaust fan motor no. 1 speed and stage (on/off)
Change PE VFD set point according to Table 14.
30
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Table 15 — PE VFD Set Point (Frequency
display board will be energized. This indicates that control sys-
tem is ready to run quick test program.
Command) for Building Pressure
VFD
SET POINT
(Hz)
CONTROL
SIGNAL
(mA)
VFD
SET POINT
(Hz)
CONTROL
SIGNAL
(mA)
IMPORTANT: Do not allow unit control circuit to
remain energized with 20 showing on display for more
than 2 minutes. If display button is not pressed within
this time period, control will attempt to start unit.
PRESSURE
(in. wg)
PRESSURE
(in. wg)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.0
3.0
4.00
4.80
5.60
6.40
7.20
8.00
8.80
9.60
10.40
11.20
0.00
–0.05
–0.10
–0.15
–0.20
–0.25
–0.30
–0.35
–0.40
–0.45
–0.50
30.0
33.0
36.0
39.0
42.0
45.0
48.0
51.0
54.0
57.0
60.0
12.00
12.80
13.60
14.40
15.20
16.00
16.80
17.60
18.40
19.20
20.00
6.0
9.0
For each step of the 33-step program, display button must
be pressed twice. On first press, step number is displayed;
second press initiates required action and appropriate code is
displayed.
NOTE: The step number is a numeral followed by a decimal
point (a 2-digit number has a decimal point after each
numeral). The action code number is one or 2 digits with no
decimal point(s).
12.0
15.0
18.0
21.0
24.0
27.0
IMPORTANT: Once quick test is initiated, display but-
ton must be pressed at least once every 10 minutes for
control to remain in Quick Test mode. If button is not
pressed within this time, control will attempt to start the
unit.
START UNIT
To start unit:
To recheck any step in quick test program, control must be
recycled by turning unit control switch off for a few seconds,
and then turning it back on again. Restart quick test program as
described above and proceed through quick test steps. Press
display button twice for each step until step to be rechecked is
reached.
1. Close the unit-mounted ON/OFF switch (located in the
main control box).
2. Close the field-supplied and -installed timeclock (or con-
trol) switch (contacts located at Terminals 1 and 2 (TB3
for 034-048, TB4 for 054-104).
The quick test program is divided into 3 sections as de-
scribed below and shown in Tables 16-18.
1. Quick Test Steps 1.-1.3. — Unit Configuration and
Switch Check
IMPORTANT: The field-supplied and installed switch
(or timeclock) MUST BE CLOSED to put unit in
Occupied mode. Unit WILL NOT START until this is
accomplished.
The microprocessor in unit control system is pro-
grammed by 2 switch assemblies located on processor
board (Fig. 1). The configuration header is factory set and
cannot be changed in the field. The DIP switch assembly
contains 8 microswitches that must be set in accordance
with the various options selected by the customer. All
DIP switches should be checked and set to proper posi-
tion for options selected prior to the quick test. See Con-
figuration of Header and DIP Switch Assembly section
on page 5 for factory switch settings. The DIP switch
functions and display codes are shown in Table 16.
3. Initialization mode begins (see Operating Information
section on page 34 for complete description of sequences
and display codes).
4. Run Quick Test. If the display button is pressed during
the initialization mode period, the unit will run its self-
diagnostic routine. When this is in effect, an 88 will ap-
pear in the display screen. Refer to Quick Test Program
section below, for instructions on completing the Quick
Test program.
Quick Test Program — Turn on power to unit.
2. Quick Test Steps 1.4.-2.3. — Thermistor and Set Point
Potentiometer Check
IMPORTANT: The field-supplied switch (or timeclock)
must be closed to put unit into the occupied mode.
In these steps, the microprocessor checks resistance val-
ues of all sensors and set point potentiometers to ensure
that they are functional, connected properly, and set with-
in proper range for unit configuration.
Nominal resistance values for all sensors range from
363,000 to 219 ohms in accordance with Table 19. Nor-
mal display code for good sensors and potentiometers
is 1. A display code of 0 indicates a faulty potentiometer,
thermistor or wiring. A 0 display also indicates that op-
tion is not being used.
The quick test program utilizes the 2-digit LED display (see
Fig. 6) on the set point board to show status of all input and
output signals to microprocessor. Display action and quick test
procedures are described below.
The quick test program is a 33-step program that provides a
means of checking all input and output signals of controls prior
to unit start-up. This check ensures that all control options,
thermistors, and control switches are in proper working order.
When unit control circuit is switched to Occupied mode, a
20 will appear on the display. Immediately press display button
once. An 88 will appear on the display and alarm light on
Table 17 shows thermistor and set point potentiometer
functions and quick test display codes.
31
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Table 16 — Quick Test, Unit Configuration and Switch Check
QUICK
TEST
NORMAL
DESCRIPTION
Type Unit — Air-Cooled VAV
CONTROL SWITCH
Configuration Header
DISPLAY
STEP NO.
1.
2.
01
2
No. of Compressors
Configuration Header
DIP Switch No. 6 and 7
No. of Unloaders
(034,038,048-088)
3.
2
1
(044, 104)
4.
5.
60
60-Hertz Power
Configuration Header
DIP Switch No. 2
0 — No Reset (Switch Off)
1 — Reset On (Switch On)
0 or 1
0 — No Economizer (Switch Off)
1 — Economizer On (Switch On)
DIP Switch No. 3
DIP Switch No. 4
DIP Switch No. 5
6.
7.
0 or 1
0 or 1
0 — No Warm-Up (Switch Off)
1 — Warm-Up Used (Switch On)
0 — Demand Limit Not Used
(Switch Off)
1 — Demand Limit Used
(Switch On)
8.
0 or 1
0 — Enthalpy Switch Open
1 — Enthalpy Switch Closed
EC
9.
0 or 1
1.0.
1.1.
1.2.
1.3.
1
1
1
1
1 — Low-Pressure Switch Closed
1 — Low-Pressure Switch Closed
No Circuit 1 Oil Pressure Switch
No Circuit 2 Oil Pressure Switch
Low-Pressure Switch 1
Low-Pressure Switch 2
None*
None*
LEGEND
DIP — Dual, In-Line Package
EC — Enthalpy Control
VAV — Variable Air Volume
*Units are not equipped with oil pressure switches.
32
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Table 17 — Quick Test, Thermistor and Potentiometer Check
QUICK
TEST
STEP NO.
NORMAL
DISPLAY
THERMISTOR OR
POTENTIOMETER*
DESCRIPTION
1 — Thermistor OK
Supply Air
1.4.
1.5.
1.6.
1.7.
1
1
1
1
0 — Thermistor Faulty
Thermistor (T1)
1 — Thermistor OK
0 — Thermistor Faulty
1 — Thermistor OK
0 — Thermistor Faulty
1 — Thermistor OK
0 — Thermistor Faulty
Return Air
Thermistor (T2)
Circuit 1 Condenser Thermistor
(T3)
Circuit 2 Condenser Thermistor
(T4)
1 — Thermistor or Potentiometer OK
0 — Thermistor or Potentiometer Faulty or
Option not used
Accessory Space Temperature Thermistor (T10)
or Accessory Reset Potentiometer (P7)
1.8.
1
1 — Potentiometer OK
Supply-Air Set Point
Potentiometer (P1)
Accessory Reset Limit
Potentiometer (P3)
Accessory Demand Limit
Potentiometer (P4)
1.9.
2.0.
2.1.
1
1
1
0 — Potentiometer Faulty
1 — Potentiometer OK
0 — Potentiometer Faulty or Option not used
1 — Potentiometer OK
0 — Potentiometer Faulty or Option not used
1 — Potentiometer OK
Minimum Position
Economizer
2.2.
2.3.
1
1
0 — Potentiometer Faulty or Option not used
Potentiometer (P5)
1 — Potentiometer OK
0 — Potentiometer Faulty or Option not used
Warm-Up Set Point
Potentiometer (P6)
*Potentiometer P2 is not listed since it is not part of the quick test. If on unit start-up a Code 83 is displayed, check potentiometer P2.
Table 18 — Quick Test, Output Relay Check
QUICK
NORMAL
DISPLAY
TEST
DESCRIPTION
RELAY NUMBER
STEP NO.
2.4.
2.5.
2.6.
2.7.
2.8.
2.9.
3.0.
3.1.
3.2.
3.3.
1
1 — Open Economizer or Open Relay if no Economizer
1 — Close Economizer or Close Relay if no Economizer
1 — Energize Fan Relay and Heat Relay
Energize Stage 1 Condenser Fan(s)
Energize Stage 2 Condenser Fan(s)
Energize Compressor 1†
K7
1
K8
1
K9* and K10
1
K11
K12
K1
1
0 then 1 then 0
0
Energize Unloader 2; Not Used (044, 104)
Energize Unloader 1
K2
0
K3
0 then 1 then 0
0
Energize Compressor 2†
K5
Not Used
K6
LEGEND
CR — Control Relay
*K9 (fan relay) will remain on for duration of quick test.
†Compressor will be energized for 10 seconds. Zero indicates open CR; 1 indicates closed CR.
33
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Table 19 — Sensor Resistance Values
enthalpy is good. As long as the outdoor-air enthalpy is accept-
able, no mechanical cooling will take place until the economiz-
er dampers are fully open. The rest of the steps and the opera-
tional sequence vary due to the number of compressors and un-
loaders. Refer to Operating Sequence section on page 35 for
the unit stages of operation.
CODES 20 THROUGH 30 AND 88, OPERATIONAL STA-
TUS — These codes indicate special operational modes, such
as initialization, morning warm-up, temperature reset, demand
limit, or an internal failure of the board. Codes 23-25 and
27-29 are not used on these units.
Initialization — When the control is turned on, the display
shows a 20 for approximately 2 minutes to indicate that the
control is in the initialization mode. During this time, the econ-
omizer dampers open and close to determine the resistance
range of the economizer position potentiometer (P2) for full
economizer operation. The processor loads the necessary con-
stants for proper unit operation and checks the thermistors and
other potentiometers for their values and validity. After the ini-
tialization period, the display screen goes blank until the dis-
play button is pressed. If the display button is pressed during
the 2-minute initialization period, the control goes into the
Quick Test mode.
Temperature Reset — If the unit is equipped with the accesso-
ry temperature reset package, and DIP switch 2 is in the ON
position, the unit will reset the supply-air temperature to a cal-
culated value when necessary. When this condition is in effect,
a 21 will appear in the display.
TEMP RESISTANCE TEMP RESISTANCE TEMP RESISTANCE
(F)
(Ohms)
(F)
(Ohms)
(F)
(Ohms)
–60
–55
–50
–45
–40
–35
–30
–25
–20
–15
–10
–5
362,640
297,140
245,245
202,841
168,250
139,960
116,820
98,420
82,665
69,685
58,915
50,284
42,765
36,475
31,216
26,786
23,164
19,978
17,276
14,980
13,085
45
50
11,396
9,950
8,709
7,642
6,749
5,944
5,249
4,644
4,134
3,671
3,265
2,913
2,600
2,336
2,092
1,879
1,689
1,527
1,377
1,244
1,126
150
155
160
165
170
175
180
185
190
195
200
205
210
215
220
225
230
235
240
1,020
929
844
768
699
640
585
535
490
449
414
380
350
323
299
276
255
236
219
55
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
135
140
145
0
5
10
15
20
25
30
35
40
3. Quick Test Steps 2.4.-3.3. — Output Relay Check
These quick test steps allow microprocessor to check out-
put signals from relay boards in unit control system. In
addition, operation of all the condenser fans, compres-
sors, and economizer (if equipped) are checked at each
step.
Normal display for Steps 2.4. through 2.8. is 1. In Steps
2.9. through 3.2., each compressor and unloader is started
and allowed to run for approximately 10 seconds. At
startup, a 0 will appear on the display followed by a
1 (Steps 2.9. and 3.2.) in a few seconds. Steps 3.0. and
3.1. will always be 0 since there are unloaders, and Step
3.3. will always be zero since it is not used.
At end of the 10-second time period, a 0 will return to the
display board indicating that test step has been success-
fully completed (Steps 2.9. and 3.2.). The 1 indicates that
was tested.
Fan and compressor operating sequence for quick test
Steps 2.4. through 3.3. are shown in Table 18.
Demand Limit — If the unit is equipped with the accessory
demand limit control module or the field-supplied, single-step
demand limit potentiometer, and DIP switch 5 is in the ON
position, the unit will limit the capacity stages to a predeter-
mined value. When this condition is in effect, a 22 will appear
in the display.
Morning Warm-Up — If the morning warm-up heat routine is
enabled using DIP switch 4, and conditions of the occupied
space warrant, the unit will begin the morning warm-up rou-
tine. When this condition is in effect, a 26 will appear in the
display.
If the quick test steps do not operate as described above, a
defect exists in one or more of the following: relay being test-
ed, electronic control, or unit wiring. Determine problem and
correct.
Internal Failure — If the unit detects an internal fault (such as
a time measurement failure), or detects an incorrect voltage on
an input channel, a 30 will be displayed, and the unit will shut
down.
Quick Test — If the display button is pressed during the ini-
tialization period of the processor, the unit will run its self-diag-
nostic routine. When this is in effect, an 88 will appear in the
display screen.
CODES 51 THROUGH 87, DIAGNOSTIC INFORMATION
— These codes indicate diagnostic information when there is a
unit problem such as a faulty thermistor, potentiometer, or
compressor fault. Refer to Diagnostic Codes section on
page 45 for more details. Codes 53, 54, 57, 58, 61, 62, 65-69,
73, 74, and 77-80 are not used on these units.
Under normal operation, only the stage number is displayed
when the display button is pressed. If a status or overload code
is displayed, the display will rotate every 2 seconds and will
display up to 3 codes. Overload information takes priority over
all other codes. The codes are stored in the microprocessor as
long as the board remains energized.
OPERATING INFORMATION
Digital Display — The VAV control system uses a 2-digit
LED display located on the display board to display operation-
al information and diagnostic codes.
CODES 0 THROUGH 8, CAPACITY STEPS — These codes
indicate the number of cooling stages active at the time the dis-
play button is pressed. The highest code indicated on the dis-
play will be 6 for the 034,038 and 048-088 units, 4 for the 044
units, and 8 for the 104 units.
Capacity steps are directly related to pin terminal connector
J6 output. At step zero, the unit has no mechanical cooling on,
and the economizer may or may not be operating (depending
on the outdoor air conditions). Once a cooling load is detected
(T1 thermistor reads above the supply-air set point), the econo-
mizer will begin modulating to meet the load if the outdoor
34
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Compressors, unloaders, and condenser fans will be cycled
to maintain a supply-air temperature 2° F below the potentiom-
eter P1 set point once the mechanical cooling stages begin.
Each unit’s cycling is slightly different, and is based on the
number of compressors and unloaders. The operational loading
sequence of compressors is as follows:
During the start-up of the lead compressor for each circuit,
the low-pressure switch will be bypassed for 120 seconds to
prevent nuisance trips of the low-pressure switch. After start-
up, a low-pressure trip will be ignored for 30 seconds by the
processor.
SIZE 034,038 AND 048-088 UNITS — These units have 2
compressors and 2 unloaders on compressor 1. See Fig. 42 and
43 for compressor and condenser-fan motor locations. The
operating sequence is as follows:
Stage 1 Relays K1, K2, and K3 are energized. Compressor
no. 1 starts with both unloaders energized. Compres-
sor no. 1 runs at 1/3 capacity. The crankcase heater for
this compressor has been deenergized, and the first
stage of condenser fans have been energized. Out-
door (condenser) fan motor no. 1 (OFM1) has started
on all units.
Operating Sequence — The sequence presented be-
low assumes that the unit is equipped with heat for morning
warm-up and an economizer. If these items are not enabled
with the appropriate DIP switches, the processor bypasses
these subroutines. This sequence is also based on an EPROM
(erasable, programmable, read-only memory) processor chip
with the identification ‘HT204485-1-XX,’ where ‘XX’ is re-
placed by a 2-digit number representing the current software
version. See Fig. 1 for EPROM chip location.
When power is applied to the occupied mode relay (OMR)
through the closure of either a field-installed timeclock or a
field-installed switch in the occupied space, the unit will begin
its initialization mode.
A 20 will appear in the display screen, and the initialization
period will last approximately 2 minutes. During this time, the
economizer dampers open and close to determine the resis-
tance range for full economizer operation of the economizer
position potentiometer (P2). The processor loads the necessary
constants for unit operation, and also checks the thermistors
and other potentiometers for their values and validity. After the
initialization period, the screen goes blank until the display but-
ton is pressed.
Stage 2 Relays K1 and K3 are energized. Compressor no. 1 is
running with unloader 1 (U1) energized. The com-
pressor is now operating at 2/3 capacity.
Stage 3 Relay K1 is energized. Compressor no. 1 is fully
loaded.
Use caution during this time (after initialization when the
screen is blank), because the unit supply and return fans
could start at any time. Personal injury could result from
contact with rotating fans.
Stage 4 Relays K1, K2, K3, and K5 are energized. Compres-
1
sor no. 1 is running at /3 capacity, and compressor
Once the initialization period is complete, the supply fan be-
gins operation. While the fan is operating, the economizer
dampers are closed and return air from the building is being
circulated. After 2 minutes, the processor checks the resistance
value of thermistor T2. If T2 temperature sensed is 5° F or
more below the set point of the morning warm-up potentiome-
ter (P6), the unit will begin the morning warm-up routine, and
a 26 will be displayed.
no. 2 is running at full capacity. The crankcase heater
for compressor no. 2 has been deenergized.
Stage 5 Relays K1, K3, and K5 are energized. Compressor
no. 1 is running at 2/3 capacity, and compressor no. 2
is running at full capacity.
Stage 6 Relays K1 and K5 are energized. Both compressors
are running fully loaded.
Size 034 and 038 units have 2 condenser fans, one of which
is controlled by the microprocessor. The OFM1 is energized
with compressor no. 1. The OFM2 is controlled by the proces-
sor and is cycled based on input from circuit thermistor T3 or
T4.
Size 048 units have one fan that can be controlled by the
processor. The other 2 are controlled by the compressors. The
OFM1 is energized by compressor no. 1, and OFM3 is ener-
gized by compressor no. 2. The OFM2 is cycled by the proces-
sor based on input from either circuit (thermistors T3 and T4).
Unit heat will be energized through the heat interlock relay
(HIR), and all of the occupied space air terminals will open.
The unit will continue heating the space until the return-air
temperature is within 2° F of set point. The unit will then shut
off the heat and continue to circulate air. The unit will cycle in
and out of the Heating mode until the return-air temperature
reaches the morning warm-up set point (P6). Once morning
warm-up has been terminated, the unit cannot return to morn-
ing warm-up until the unit is powered down and restarted. This
action signals a return to the Occupied mode.
NOTE: Occupied heat is NOT AVAILABLE on these units.
On size 054,064 units, the first 2 condenser fans energize
with the compressors; compressor no. 1 controls OFM1, and
compressor no. 2 controls OFM2. The OFM3 and OFM4 are
staged by the microprocessor based on the condensing temper-
ature input from thermistor T3 or T4.
On size 074-078 units, the first 3 condenser fans energize
with the compressors; compressor no. 1 controls OFM1, and
compressor no. 2 controls OFM2 and OFM3. The OFM4 and
OFM5 are staged by the microprocessor based on condensing
temperature input from either circuit’s T3 or T4 thermistor.
On Size 088 units, the first 4 condenser fans energize with
the compressors; compressor no. 1 controls OFM1 and OFM3,
and compressor no. 2 controls OFM2 and OFM4. The OFM5
and OFM6 are staged by the microprocessor based on
condensing temperature input from either circuit’s T3 or T4
thermistor.
Once out of the morning warm-up routine, the unit will be-
gin its cooling routine based on the supply-air set point (P1). At
step zero, the unit has no mechanical cooling on, and the econ-
omizer may or may not be operational. The economizer will
move to the minimum position determined by potentiometer
P5 if no cooling load is detected. Once a cooling load is detect-
ed by thermistor T1 sensing a temperature higher than the cool-
ing demand set point (P1), the economizer will begin modulat-
ing to meet the load if the outdoor enthalpy is good. The pro-
cessor will attempt to maintain a supply-air temperature of P1
± 2° F by modulating the economizer dampers.
No mechanical cooling will take place until the economizer
dampers are fully open (if the outdoor-air enthalpy permits). If
the economizer is unable to meet the cooling demand, then me-
chanical cooling is used in conjunction with the economizer. If
the economizer is unable to meet the load due to unacceptable
outdoor-air enthalpy, the dampers will return to the minimum
position as determined by P5.
35
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SIZE 044 UNITS — These units have 2 compressors and 1
unloader on compressor no. 1. See Fig. 42 for compressor and
condenser fan motor locations. The unit operating sequence is
as follows:
Stage 5 Relays K1, K3, K5, and K5 are energized. Compres-
2
sor no. 1 runs at /3 capacity and compressors no. 2
and no. 4 are running at full capacity. The crankcase
heater on compressor no. 4 is deenergized. Fans
OFM1, OFM2, OFM3, and OFM4 are operating.
Stage 1 Relays K1 and K3 are energized. Compressor no. 1
starts with the unloader energized. Compressor no. 1
Stage 6 Relays K1, K5, and K6 are energized. Compressors
no. 1, no. 2, and no. 4 are running fully loaded.
1
is running at /2 capacity. The crankcase heater on
compressor no. 1 has been deenergized, and the first
stage condenser fan has been energized. Outdoor
(condenser) fan motor no. 1 (OFM1) has started.
Stage 7 Relays K1, K2, K3, K5, and K6 are energized. Com-
pressor no. 1 runs at 2/3 capacity and compressors no.
2, no. 3, and no. 4 are running at full capacity. Fans
OFM1, OFM2, OFM3, and OFM4 are operating.
Crankcase heater for compressor no. 3 is deener-
gized.
Stage 8 Relays K1, K2, K5, and K6 are energized. Compres-
sors no. 1, no. 2, no. 3, and no. 4 are running fully
loaded.
On size 104 units, the first 4 condenser fans energize with
the compressors; circuit no. 1 compressors control OFM1 and
OFM3, and circuit no. 2 compressors control OFM2 and
OFM4. The OFM5 and OFM6 are staged by the microproces-
sor based on condensing temperature input from either circuit’s
T3 or T4 thermistor.
Stage 2 Relay K1 is energized. Compressor no. 1 is fully
loaded.
Stage 3 Relays K1, K3, and K5 are energized. Compressor
no. 1 is running at 1/2 capacity, and compressor no. 2
is running at full capacity. The crankcase heater for
compressor no. 2 is deenergized. The second stage
condenser fan has been energized. Both OFM1 and
OFM3 are operating.
Stage 4 Relays K1 and K5 are energized. Both compressors
are running fully loaded.
Size 044 units have one fan that can be controlled by the
processor. The other 2 are controlled by the compressors. The
OFM1 is energized by compressor no. 1, and OFM3 is ener-
gized by compressor no. 2. The OFM2 is cycled by the proces-
sor based on input from either circuit (thermistors T3 and T4).
SIZE 104 UNITS — These units have 4 compressors and 1
unloader on compressor no. 1. See Fig. 43 for compressor and
condenser fan motor locations. The unit operating sequence is
as follows:
Stage 1 Relays K1 and K3 are energized. Compressor no. 1
starts with unloader energized. Compressor no. 1 runs
at 2/3 capacity. The crankcase heater for this compres-
sor has been deenergized, and first stage of condenser
fans has been energized. Outdoor (condenser) fan
motor no. 1 (OFM1) and outdoor fan motor no. 3
(OFM3) have started.
Head Pressure Control — All units have as standard a
basic head pressure control function which allows the units to
operate in cooling down to 45 F. If cooling is required at out-
door ambient temperatures lower than 45 F, refer to accessory
head pressure control literature for details.
Head pressure control is handled by the processor. The pro-
cessor attempts to maintain the head pressure by cycling the
condenser-fan motors. No condenser fans will be running with-
out a call for mechanical cooling. Thermistors T3 and T4 pro-
vide the condensing temperature information to the processor.
These VAV rooftop units have dual refrigeration circuits, and
the higher circuit temperature will govern unit operation. If the
condensing temperature is above 133 F (236 psig), a condenser
fan stage will be added. If the condensing temperature is 78 F
(142 psig) or less, the number of condenser fans operating will
be decreased. After each fan stage, the processor will wait one
minute for the head pressures to stabilize before changing
again, unless thermistor T3 or T4 senses a temperature greater
than 125 F (278 psig), in which case all condenser fans are
started.
Stage 2 Relay K1 is energized. Compressor no. 1 is fully
loaded.
Stage 3 Relays K1, K3, and K5 are energized. Compressor
no. 1 runs at 2/3 capacity and compressor no. 2 is run-
ning at full capacity. The crankcase heater for com-
pressor no. 2 is deenergized. The first stage of
condenser fans on circuit 2 has been energized. Fans
OFM1, OFM2, OFM3, and OFM4 are operating.
During start-up, if the outdoor ambient is above 70 F (as
sensed by thermistor T3 or T4), the first-stage, processor-
controlled fans are turned on to prevent excessive discharge
pressures.
Stage 4 Relays K1 and K5 are energized. Both compressors
no. 1 and no. 2 are running fully loaded.
044 AND 048 UNITS
034 AND 038 UNITS
LEGEND
OFM
— Outdoor (Condenser) Fan Motor
Fig. 42 — Component Arrangement, 034-048 Units
36
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054, 064 UNITS
054-088 UNITS
074, 078 UNITS
088, 104 UNITS
104 UNITS
Fig. 43 — Component Arrangement, 054-104 Units
37
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As the economizer actuator opens past 17% open, auxiliary
switch DMS1 closes, energizing fan contactor PEC1. Fan mo-
tor no. 1 starts and runs.
Capacity of fan no. 1 is controlled by the position of the out-
let damper. As building pressure increases above set point,
the DPS will close its contact and drive the power exhaust
damper motor (PEDM) open until set point is achieved. DPS
then opens its control contacts and PEDM maintains current
position.
When space demand moves PEDM to 90% of full-open po-
sition, auxiliary switch PEDMS closes, energizing fan contac-
tor PEC2. Fan motor no. 2 starts and runs. Increased exhaust
airflow will lower space pressure, causing DPS to drive PEDM
back towards its closed position, until the set point is achieved.
If space pressure decreases until PEDM position is reduced
to 10% of open position, PEDMS will open, deenergizing fan
contactor PEC2 and shutting off fan no. 2.
Supply Fan Control with IGV — In most VAV units,
the supply fan static pressure is controlled by inlet guide vanes.
The inlet guide vanes operate independently from the micro-
processor. The supply static pressure is controlled by a differ-
ential pressure switch.
For example, assume that set point on supply fan differen-
tial switch is 1.9 in. wg. If pressure in supply duct goes above
1.9 in. wg, switch will make to the normally open contact and
energize inlet guide vane motor to drive inlet guide vanes to a
more closed position, thus reducing airflow and lowering duct
pressure. Once set point pressure is reached, switch will open
and deenergize inlet guide vane motor. If pressure in supply
duct is below 1.9 in. wg, the switch will make to the normally
closed contact and energize inlet guide vane motor to drive in-
let guide vane to a more open position; increasing airflow and
raising duct pressure. Once again, once desired pressure has
been reached, switch will open and deenergize inlet guide vane
motor. How far above or below the set point setting the switch
goes before energizing depends on setting of null span (null
span is pressure change that can be made without contacts
opening or closing). If null span is at maximum position, pres-
sure will vary from 0.17 in. wg to 0.31 in. wg depending on set
point (if set point is at minimum setting, null span will be
0.17 in. wg, while if it is at maximum position, the null span
will be 0.31 in. wg) before switch acts. If null span is adjusted
to a minimum setting, duct pressure will vary from 0.06 in. wg
to 0.11 in. wg (again depending on switch set point) before
switch acts. Setting null span to minimum position will result
in a smaller pressure fluctuation than if it is set at maximum
position.
High Capacity Modulating Power Exhaust
(48FM and 50 FM,FS Units) — The high-capacity
modulating power exhaust assembly consists of two parallel
and independent belt-drive large diameter forward curve fans.
The fans, motors, and drives are located in a cabinet extension
(not over the return air opening of the unit), in a plenum be-
neath the outside air intake plenum. The fans discharge hori-
zontally out the back of the unit through individual barometric
backdraft dampers with hoods. Operation is interlocked with
economizer operation. Space pressure is monitored by a
factory-installed differential pressure transducer. See Fig. 48
for component locations and sheet metal details.
The high-capacity modulating power exhaust is also avail-
able on horizontal 50FS units. Return duct opening is located
on the left-hand side of the unit; exhaust air exits the unit out
the back.
Control of the high-capacity modulating power exhaust sys-
tem is accomplished via a combination modulated capacity
fan/staged fan. Modulation is provided by a variable frequency
drive controlling the direct output to fan no. 1 and controlling
the ON/OFF status of fan no. 2.
Fan no. 1 is equipped with a Variable Frequency Drive,
matched to the motor size. VFD output is determined by the
VFD’s internal PID logic in response to actual space pressure
as monitored by the Building Pressure (BP) transducer. Set
point for BP control is established at the PE VFD. Available set
point range is –0.50 to +0.50 in. wg. Building Pressure is
sensed by a pick-up (field-supplied and -installed) located in
the occupied space and connected to the BP transducer by
1/4-in. tubing (field-supplied and -installed).
Supply Fan Control with VFD — When equipped
with the VFD option, the supply fan static pressure is con-
trolled by modulating the fan wheel speed. The VFD operates
independently from the microprocessor. A duct pressure trans-
ducer monitors duct static pressure. The transducer output (4 to
20 mA) is directed into the VFD. The VFD adjusts supply fan
motor speed (which changes wheel speed) as measured duct
pressure varies from set point as established at the VFD. The
VFD will modulate fan speed until the duct pressure set point is
achieved.
NOTE: The VFD will always provide the proper phase
sequence to the supply fan motor. This motor will operate in
proper rotation regardless of the phase sequence to the unit. If,
upon start-up, the outdoor fans operate backwards but the
indoor fan operates in the correct direction, reverse any two
leads to the main terminal block. All fans will then operate in
the correct direction.
Operation of the modulating power exhaust is a combina-
tion modulating/staged control, with fan no. 1 providing modu-
lating control from 0 to 50% of total exhaust capability, and fan
no. 2 being staged On/Off (for a step of 50% of total exhaust
capability) according to VFD output level on fan no. 1.
As the economizer actuator opens past 17% open, auxiliary
PEC1. Fan motor no. 1 starts and runs.
Capacity of fan no. 1 is controlled by the output level from
the BP VFD. As building pressure increases above set point,
the VFD logic will increase the output level to fan no. 1 until
set point is reachieved.
When space demand moves PE VFD output to 100%
(60 Hz), VFD internal relay closes, energizing fan contactor
PEC2. Fan motor no. 2 starts and runs. Increased exhaust air-
flow will lower space pressure, causing PE VFD to reduce its
output to fan no. 1 until set point is reachieved.
Modulating Power Exhaust (48FK,JK and
50FK,JK Units Option or Accessory) — The pow-
er exhaust assembly consists of two parallel and independent
belt-drive forward curve fans. The fans, motors, and drives are
located over the return air opening of the unit, in a plenum be-
neath the outside air intake plenum. The fans discharge air hor-
izontally out the back of the unit through individual barometric
backdraft dampers with hoods. (See Fig. 44 and 45.) Operation
is interlocked with economizer operation. Sheet metal installa-
tion is shown in Fig. 46 and 47.
Fan no. 1 is equipped with a variable position discharge
damper located in the outlet of the fan housing. This damper is
controlled by an actuator (PEDM), based on signals from the
building pressure differential pressure switch (DPS). Available
range on the DPS is -0.50 to +0.50 in. wg, adjustable. Building
pressure is sensed by a pick-up (field-supplied and -installed)
located in the occupied space.
If space pressure decreases until PE VFD output is reduced
to 25% of maximum output (15 Hz), VFD internal relay will
open, deenergizing fan contactor PEC2 and shutting off fan
no. 2.
Operation of the modulating power exhaust is a combina-
tion modulating/staged control, with fan no. 1 providing modu-
lating control from 0 to 50% of total exhaust capability, and fan
no. 2 being staged On/Off (for a step of 50% of total exhaust
capability) according to damper position on fan no. 1.
Unit Staging — Compressor loading and unloading se-
quences are shown in Table 20.
38
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Fig. 44 — Modulating Power Exhaust Component Locations; Sizes 034-048
39
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40
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Fig. 46 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; Sizes 034-048
Fig. 47 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; Sizes 054-104
41
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PE VFD
ACCESS DOOR
AUXILIARY
CONTROL BOX
LARGE ECONOMIZER
HOOD LOCATION
EXHAUST
AIR
POWER EXHAUST
ACCESS DOOR
SMALL ECONOMIZER
HOOD LOCATION
Fig. 48 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; 48FM and 50FM,FS Units
Table 20 — Compressor Loading and Unloading Sequences
SIZE 034 UNITS
COOLING
STAGE
Lead Circuit
Unloader
U1
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
ON
OFF
ON
ON
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
4
6
8
0
17
33
50
67
OFF
OFF
ON
ON
10
12
83
100
OFF
SIZE 038 UNITS
COOLING
STAGE
Lead Circuit
Unloader
U1
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
ON
OFF
ON
ON
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
4
6
6
0
14
28
42
72
OFF
OFF
ON
ON
8
10
86
100
OFF
42
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Table 20 — Compressor Loading and Unloading Sequences (cont)
SIZE 044 UNITS
COOLING
STAGE
Lead Circuit
Unloader
Lag Circuit
Active
Percent
Cylinders
Capacity
Comp 1
Comp 2
U1
OFF
ON
OFF
ON
0
1
2
3
4
OFF
ON
ON
ON
ON
OFF
OFF
OFF
ON
0
2
4
6
8
0
25
50
75
100
OFF
ON
SIZE 048 UNITS
COOLING
STAGE
Lead Circuit
Unloader
U1
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
ON
OFF
ON
ON
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
4
6
6
0
19
38
58
62
OFF
OFF
ON
ON
8
10
81
100
OFF
SIZE 054 UNITS
COOLING
STAGE
Lead Circuit
Unloader
U1
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
OFF
ON
ON
ON
ON
ON
OFF
ON
ON
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
0
2
4
6
10
12
0
20
40
60
80
ON
100
SIZE 064 UNITS
COOLING
STAGE
Lead Circuit
Unloader
U1
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
ON
OFF
ON
ON
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
4
6
8
0
17
33
50
67
OFF
OFF
ON
ON
10
12
83
100
OFF
SIZE 074, 078 UNITS
COOLING
STAGE
Lead Circuit
Unloader
U1
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
ON
OFF
ON
ON
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
4
6
8
0
14
29
43
71
OFF
OFF
ON
ON
10
12
86
100
OFF
43
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Table 20 — Compressor Loading and Unloading Sequences (cont)
SIZE 088 UNITS
COOLING
STAGE
Lead Circuit
Unloader
U1
Lag Circuit
Active
Cylinders
Percent
Capacity
Unloader
U2
Comp 1
Comp 2
0
1
2
3
4
5
6
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
ON
OFF
ON
ON
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
0
2
4
6
8
0
16
33
50
66
OFF
OFF
ON
ON
10
12
83
100
OFF
SIZE 104 UNITS
Lag Circuit
COOLING
STAGE
Lead Circuit
Unloader
U1
Active
Cylinders
Percent
Capacity
Comp 1
Comp 3
Comp 2
Comp 4
0
1
2
3
4
5
6
7
8
OFF
ON
ON
ON
ON
ON
ON
ON
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
0
4
6
10
12
14
16
18
20
0
20
30
50
60
70
80
90
100
OFF
ON
•
•
•
Blown fuse in the control power feed.
Open control circuit fuse.
TROUBLESHOOTING
By using the display module, actual operating conditions of
the unit are displayed while it is running. The Quick Test func-
tion allows proper operation of compressors, compressor un-
loaders, fans, and other components to be checked while unit is
stopped. If an operating fault is detected, an alarm is generated
and an alarm code(s) is displayed. For checking specific items,
see Table 21.
Operation of the unit blocked by the demand limit
function.
•
•
•
Unit supply-air temperature (T1) thermistor failure.
Supply-air fan is not operating.
High duct static pressure.
Single Circuit Stoppage — If a single circuit stops,
there are several potential causes:
Checking Display Codes — To view the digital dis-
play codes, press the button located to the right of the LED dis-
play/set point board in the control box. See Table 22 for Opera-
tional Status Codes. See Table 23 for Diagnostic Codes.
•
•
•
•
•
•
Open contacts in the compressor high-pressure switch.
Low refrigerant pressure.
Thermistor failure.
Unit supply-air temperature thermistor (T1) failure.
Compressor circuit breaker trip.
Operation of the circuit blocked by the demand limit
function.
Complete Unit Stoppage — If the unit is off, there are
several conditions that can cause this situation to occur:
•
•
•
•
Remote ON/OFF circuit in Unoccupied mode.
Unit ON/OFF switch moved to OFF position.
Programmed schedule at the timeclock.
General power failure.
Table 21 — Controls Troubleshooting
SYMPTOM(S)
PROBABLE CAUSE(S)
SOLUTION(S)
Controls do not seem
to be operating.
Remote on-off function may be
keeping controls off.
Check status.
1. Circuit breaker open.
1. Find cause and reset circuit breaker.
2. Find cause and reset.
1. Find cause and reset circuit breaker.
2. Correct operation.
Evaporator fan does not run.
Compressor does not run.
2. Inverter overload (if equipped).
1. Circuit breaker is open.
2. There is no demand for cooling.
3. The control is locking out cooling operation.
3. Check rotating display for alarm codes. Resolve
alarm cause and reset control by changing to
standby and back to run mode.
4. Demand Limit in effect.
Circuit breaker is open.
4. Check Demand Limit Settings.
Condenser fans do not
turn on.
Cooling demand exists and
economizer modulates, but
compression is not operating.
Find cause and reset circuit breaker
Correct operation.
Compression cannot be initiated
until economizer damper is 90% open.
44
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Table 22 — Operation Status Codes
CODES 51, 52, 55, 56: COMPRESSOR FAILURE — If con-
trol relay (CR) opens while compressor should be operating,
compressor will stop and microprocessor will energize alarm
light and display a code of 51 , 52 , 55 or 56 (depending on
compressor) when display button is pushed. The compressor
will be locked off; to reset, the ON-OFF switch must be turned
to OFF and then to ON position.
If lead compressor in a refrigerant circuit is shut down, the
other compressor in that circuit will also be shut down and
locked off. Only the error code for the lead compressor will be
displayed.
CODE
MEANING
0 cooling stages active
1 cooling stage active
2 cooling stages active
3 cooling stages active
4 cooling stages active
5 cooling stages active
6 cooling stages active
7 cooling stages active
8 cooling stages active
0
1
2
3
4
5
6
7
8
Code 51 is for compressor 1, and Code 55 is for compressor
2. Codes 52 and 56 are used for compressors 3 and 4, respec-
tively, on size 104 units.
Initialization mode (Allow 2 minutes
The microprocessor has also been programmed to indicate a
compressor failure if CR switch is closed when compressor is
not supposed to be on.
20
for initialization. To initiate Quick Test,
press the Display button while 20 is displayed.)
21
22
26
30
88
Temperature Reset in effect
Demand Limit in effect
If a failure occurs, the following are possible causes:
High-Pressure Switch Open — The high-pressure switch for
each compressor is wired in series with 24-v power that ener-
gizes CR. If high-pressure switch opens during operation, CR
will stop compressor and this will be detected by microproces-
sor through the feedback contacts.
Morning Warm-Up in effect
Internal failure detected
Self-diagnostic mode in effect
Restart Procedure — Before attempting to restart the
machine, check the display for alarm codes to determine the
cause of the shutdown. If the unit, circuit, or compressor stops
more than once as a result of a safety device, determine and
correct the cause before attempting to start the unit again.
After the cause of the shutdown has been corrected, unit
restart may be automatic or manual depending upon the fault.
Internal Thermostat — The internal thermostat in each 06D
compressor is also wired in series with 24-v power that ener-
gizes CR. If thermostat fails or switch opens during operation
of compressor, compressor will shut down and failure is detect-
ed through feedback contacts (size 034 and 038 only).
CR Failure — If CR fails with large relay either open or
closed, microprocessor will detect this, lock compressor off,
and indicate an error.
Diagnostic Codes — Diagnostic codes are warnings of
abnormal or fault conditions, and may cause either one circuit
or the whole unit to shut down. They are assigned code num-
bers as described below.
Relay Board Failure — If small 24-v relay on the relay board
fails, microprocessor will detect this through feedback contacts
and indicate an error.
Processor Board Failure — If hardware that monitors feed-
back switch fails and processor board fails to energize the relay
board relay to ON position, an error may be indicated.
Table 23 contains a description of each diagnostic code er-
ror and possible cause. Manual reset is accomplished by mov-
ing the ON/OFF Switch to the OFF position, then back to ON.
The control does not detect compressor circuit breaker
failures.
Wiring Problem — A wiring error or a loose wire may cause
the feedback circuit to be broken.
The 2-digit LED display is used to display the diagnostic
codes and the alarm light (located next to display) is energized
whenever a diagnostic code is tripped. When a problem is
suspected, always check the display first for diagnostic
information.
NOTE: Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80
are not used on these units.
IMPORTANT: The microprocessor memory and the dis-
play will be cleared if the power to the microprocessor is
shut off. DO NOT attempt to bypass, short, or modify
the control circuit or electronic boards in any way to cor-
rect a problem. This could result in a hazardous operat-
ing condition.
45
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Table 23 — Diagnostic Codes
ACTION TAKEN
BY CONTROL
RESET
DISPLAY
DESCRIPTION OF FAILURE
Compressor 1 failure
Compressor 2 failure
Compressor 3 failure
Compressor 4 failure
PROBABLE CAUSE
METHOD
51
55
52
56
Circuit 1 shut off
Manual
Manual
Manual
Manual
High-pressure switch or high dis-
charge gas thermostat switch
trip, compressor ground current
>2.5 amp or compressor board
relay on when it is not supposed
to be on. Wiring error between
electronic control and compres-
sor protection module.
Circuit 2 shut off
Compressor 3 shut off
Compressor 4 shut off
59
60
Loss-of-charge circuit 1
Loss-of-charge circuit 2
Circuit 1 shut off
Circuit 2 shut off
Manual
Manual
This indicates either a low refrig-
erant charge, or a loss-of-charge
switch failure.
63
64
Low oil pressure circuit 1
Low oil pressure circuit 2
Circuit 1 shut off
Circuit 2 shut off
Manual
Manual
Not used; Check jumper on pro-
cessor board.
70
Illegal unit configuration
Unit will not start
Manual
Configuration error (see Note 1).
71
72
75
Supply-air thermistor failure
Return-air thermistor failure
Circuit 1 saturated condensing thermistor
Circuit 2 saturated condensing thermistor
Reset temperature thermistor failure
Unit shut off
Auto.
Auto.
Auto.
Thermistor or resistor failure, wir-
ing error, or thermistor or resistor
not connected to the processor
board.
Use default value
Unit shut off
Unit shut off
Stop reset
76
Auto.
81
Auto.
82
83
84
85
86
87
Supply-air set point potentiometer failure
Economizer potentiometer failure
Use default value
Close economizer
Stop reset
Stop demand limit
Close economizer
Use default value
Auto.
Auto.
Auto.
Auto.
Auto.
Auto.
Potentiometer improperly con-
nected, potentiometer setting out
of range, potentiometer failure or
wiring error.
Reset limit set point potentiometer failure
Demand limit potentiometer failure
Minimum economizer potentiometer failure
Warm-up set point potentiometer failure
NOTES:
1. Illegal unit configuration caused by missing programmable header or both unloader DIP switches on.
2. All auto. reset failures that cause the unit to stop will restart when the error has been corrected.
3. All manual reset errors must be reset by turning the control switch off and then back on.
4. Valid resistance range for the thermistors is 363,000 to 585 ohms.
5. Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80 are not used on these units.
CODES 59 AND 60: LOW-PRESSURE SWITCH — These
codes are used to indicate a low-pressure switch failure.
been corrected. If a failure occurs, the following are possible
causes:
The processor monitors the low-pressure switch. If the
switch opens, either by low refrigerant charge, circuit failure,
or wiring error, the circuit is locked off. Code 59 indicates a
failure of the lead circuit, and as a result, that circuit will be
shut down. Code 60 indicates a failure of the lag circuit, and as
a result, that circuit will be shut down. These codes will only be
displayed when the display button is pressed. To reset the cir-
cuit, the ON-OFF switch must be turned to OFF, then ON
position.
CODES 63 AND 64: OIL PRESSURE SWITCH — These
codes are used to indicate an oil pressure switch failure. Since
the units do not have oil pressure switches, these codes are not
used. The terminals on the processor board must be jumpered
together or an error will occur. If these errors occur, check
jumper between J2-1 and J2-2 for a code 63, or between J2-3
and J2-4 for a code 64 to be sure jumper is properly connected.
To reset the circuit, the ON-OFF switch must be turned to OFF
and then to ON position.
CODE 70: ILLEGAL UNIT CONFIGURATION — If the
unit configuration header is not installed and properly config-
ured, and/or if DIP switches are not properly set, unit will not
start, and an error code of 70 will be indicated on display board
when display button is pushed. Check the header and DIP
switch settings.
CODES 71 TO 76: THERMISTOR/RESISTOR FAILURE —
If measured temperature of a thermistor is less than –60 F
(363,000 ohms) or greater than 180 F (585 ohms), the appro-
priate sensor error code (Table 23) will be displayed when
the display button is pushed. The unit will be shut down.
Thermistor failures will automatically reset once the error has
Thermistor or Resistor Failure — A shorted or open ther-
mistor or resistor will cause the failure.
Wiring Failure — If a wiring error exists that causes a shorted
or open circuit, this will cause a failure.
Processor Board Failure — If circuitry on processor board
fails, this could cause an error.
The codes are designated as follows:
Code 71 Supply-Air Thermistor Failure
Code 72 Return-Air Thermistor Failure
Code 73 Not used
Code 74 Not used
Code 75 Circuit 1 Saturated Condensing Thermistor
Code 76 Circuit 2 Saturated Condensing Thermistor
CODE 81: RESET THERMISTOR OR POTENTIOMETER
FAILURE — This is a unique code since the reset temperature
potentiometer (P7) is in series with the space temperature ther-
mistor (T10). If either one of these components fail, reset will
be terminated. This error will automatically reset once the situ-
ation is corrected. If an error is detected, the most probable
cause is one of the following:
•
•
•
•
Thermistor Failure — A shorted or open thermistor will
cause the failure.
Potentiometer Failure — If the potentiometer is outside
of the valid range (40 to 90 F), a failure will result.
Wiring Problem — If the circuit is open, a failure will be
detected.
Processor Board Failure — If the processor board fails
(hardware), an alarm will be detected.
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CODE 82: SUPPLY-AIR TEMPERATURE SET POINT
POTENTIOMETER FAILURE — If supply-air set point
potentiometer (P1 — located on display board) fails, control
will use a default value. A failure will cause an error code of
82 to be displayed on display board when display button is
pushed; alarm light will also be energized. A failure is deter-
mined by establishing a range of –22 F to 70 F as a valid range.
Anything outside this range will be treated as a failure. If set-
ting is outside the –22 F to 70 F range, alarm light will be ener-
gized and an error code of 82 will be displayed when display
button is pushed; the control will use a set point of 70 F. If set
point is between –22 F and 45 F, control will use a set point of
45 F and no error code will be indicated. If potentiometer
returns to normal, control will automatically reset.
CODE 85: DEMAND LIMIT POTENTIOMETER (P4)
FAILURE — Used only if demand limit is being used. If
demand limit is used, DIP switch 5 must be in the ON position.
Two types of demand limit are available: a field-supplied
and installed single-step control consisting of a 10 Kohm,
3-wire linear potentiometer and an accessory 2-step control.
The single-step control has a single potentiometer while 2-step
control has 2 potentiometers (mounted on the demand limit
board, see Fig. 28).
For both types of demand limit, the control uses only 80%
of the total potentiometer resistance. If resistance of potentiom-
eter is less than 10% or greater than 90%, alarm light will be
energized, a diagnostic code of 85 will be displayed when the
display button is pushed, and demand limit will be terminated.
If a failure occurs, it is probably due to one of the following:
Potentiometer Failure — If a potentiometer is shorted or open,
a failure will occur.
Incorrect Potentiometer Setting — A potentiometer turned
fully clockwise or counterclockwise will put potentiometer out
of range resulting in an error.
Faulty Wiring — If wiring between the potentiometer and the
processor board is incorrect, an error will occur.
DIP Switch 5 — If DIP switch 5 is in the ON position and po-
tentiometer is not installed, an error will occur.
CODE 86: MINIMUM POSITION ECONOMIZER POTEN-
TIOMETER FAILURE — If potentiometer P5 (on accessory
board) setting is less than 0% or greater than 100%, alarm light
will be energized, a code of 86 will be displayed when display
button is pushed and economizer outdoor air dampers will
move to the fully closed position.
The potentiometer full-scale resistance is 10 Kohm, but
when installed in parallel with the other 2 potentiometers on
the accessory board, measured resistance will be 3.3 Kohm.
This failure will automatically reset when potentiometer re-
turns to normal.
If a failure occurs, one of the following is the probable
cause:
DIP Switch 3 — If this switch is in the ON position and the
accessory board is not installed (accessory board is standard on
these units, so it should always be on the unit).
Incorrect Potentiometer Setting — If potentiometer is turned
fully clockwise or counterclockwise, potentiometer will be out
of the allowable range, and an error will result.
Faulty Wiring — If wiring between the potentiometer and the
processor board is incorrect, an error will occur.
Potentiometer Failure — If potentiometer is shorted or open,
potentiometer will be out of range and an error will result.
NOTE: The full range of the potentiometer is not used for the
cooling set point range of 45 F to 70 F. The full scale resistance
of the potentiometer is 10 Kohms.
If a failure occurs, one of the following is a probable cause:
Incorrect Potentiometer Setting — A potentiometer turned
fully clockwise or counterclockwise is outside the valid range
and will cause a failure.
Faulty Wiring — If wiring is incorrect between potentiometer
and processor board or display board, a failure will result.
Potentiometer Failure — If potentiometer is shorted or open, a
failure will result.
CODE 83: ECONOMIZER FEEDBACK POTENTIOME-
TER FAILURE — If potentiometer on economizer motor (P2)
fails, control will use a default value of 0% and economizer
outdoor-air dampers will close. The failure will energize alarm
light and cause an error code of 83 to be displayed when dis-
play button is pushed. This potentiometer is a 5 to 15 Kohm
potentiometer. If potentiometer returns to normal, control will
automatically reset. If a failure occurs, one of the following is
the probable cause.
Faulty Wiring — If the wiring between processor board and
potentiometer is wrong, this will cause a failure.
Potentiometer Failure — If potentiometer is shorted or open,
this will cause a failure.
Economizer Damper Stuck — The control has been pro-
grammed to indicate an error if potentiometer travel is less than
10% of the full range. This would happen if dampers or damp-
er linkage were hung up and could not move properly.
CODE 84: RESET LIMIT POTENTIOMETER FAILURE —
This code is applicable only if reset is being used. If reset is
being used, DIP switch 2 must be in the ON position. This
potentiometer (P3) is located on the accessory board. If poten-
tiometer setting is less than 0° F or greater than 80 F, alarm
light will be energized, a diagnostic code of 84 will be dis-
played if display button is pushed, and reset will be terminated.
The full-scale resistance of potentiometer is 10 Kohms, but
when installed on the accessory board in parallel with the other
2 potentiometers, measured resistance will be 3.3 Kohms. This
failure will automatically reset once potentiometer returns to
normal. If a failure occurs, one of the following is the probable
cause:
DIP Switch Problem — DIP switch 2 is in the ON position
and the accessory board is not installed (accessory board is
standard on these units so it should always be on the unit).
Incorrect Potentiometer Setting — A potentiometer turned
fully clockwise or counterclockwise is outside the valid range
and will result in a failure.
CODE 87: WARM-UP TEMPERATURE SET POINT FAIL-
URE — Applicable only if morning warm-up is used. Whether
or not unit is equipped with electric resistance heaters, use of
the morning warm-up function is recommended if the unit is
shut down at night or over weekends. In this application, cool-
ing will remain off and the outdoor-air damper will stay closed
until heat load from the occupied space elevates return-air tem-
perature to the warm-up set point. If warm-up function is used,
DIP switch 4 must be in the ON position. The potentiometer
(P6) is located on the accessory board. If potentiometer is set at
less than 0° F or more than 95 F, alarm light will be energized,
a diagnostic code of 87 will appear on the display when dis-
play button is pushed, and control will use a default value of
40 F. If setting is between 0° F and 40 F, control will use a
value of 40 F but no diagnostic code will be displayed; if set-
ting is between 80 F and 95 F, control will use a value of 80 F
but no diagnostic code will be displayed.
Faulty Wiring — If the wiring between the potentiometer and
the processor board is incorrect, a failure will result.
Potentiometer Failure — If potentiometer is shorted or open, a
failure will occur.
The potentiometer full-scale resistance is 10 Kohm, but
when wired in parallel with other potentiometers on the acces-
sory board, measured resistance is 3.3 Kohm.
47
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The failure will automatically reset once potentiometer re-
turns to normal. If a failure occurs, one of the following is the
probable cause:
DIP Switch 4 — If this switch is in the ON position and the
accessory board is not installed (accessory board is standard on
these units, so it should always be on the unit).
Incorrect Potentiometer Setting — If potentiometer is turned
fully clockwise or counterclockwise, potentiometer will be out
of the allowable range, resulting in an error.
Faulty Wiring — If the wiring between the potentiometer and
the processor board is incorrect, an error will occur.
PROCESSOR BOARD CHECKOUT — Refer to Fig. 49 and
50 for location of terminal pins and test points.
Step 1 — Check Transformer Input to the Board — Con-
nector J4 is used to connect the control transformer to the pro-
cessor board.
1. Set the volt-ohmmeter to ac voltage with a range setting
of approximately 30 v.
2. Turn control switch to ON position.
3. Check voltage at following terminals on pin terminal con-
nector J4:
TERMINALS
VOLTAGE (AC)
Potentiometer Failure — If potentiometer is shorted or open,
potentiometer will be out of range, resulting in an error.
1 to 2
4 to 6
5 to 6
5 to 4
15.3 to 20.9
16.2 to 22.0
8.1 to 11.0
8.1 to 11.0
Thermistor Troubleshooting — The VAV control
system uses thermistors to measure temperatures of the enter-
ing and supply air, as well as the saturated condensing tempera-
tures of the refrigerant circuits. The resistance versus tempera-
ture and electrical characteristics for all thermistors in the sys-
tem are identical. To obtain an accurate reading, a high-
impedance meter (such as a digital meter) must be used.
Thermistors in the VAV control system have a 5 vdc signal
applied across them any time the unit control circuit is ener-
gized. The voltage drop across the thermistor is directly pro-
portional to the temperature and resistance of the thermistor.
To determine temperatures at the various thermistor loca-
tions, disconnect the thermistor from the processor board and
measure the resistance across the appropriate thermistor using
a high-quality digital ohmmeter. Use the resistance reading to
determine the thermistor temperature.
The microprocessor has been programmed to check the op-
eration of the thermistors. If the measured temperature is out-
side of the range of –24 to 225 F or 98,010 to 282 ohms, then it
will be treated as a sensor failure and a diagnostic code will be
displayed. See Table 19 for sensor temperatures versus resis-
tance drop. It is also possible to check the operation of the ther-
mistors using the quick test routine.
4. If voltage is not within range, check primary side.
115-v transformer — 104 to 127 vac
230-v transformer — 207 to 254 vac
5. If primary voltage is not correct, check system fuse, trans-
former, ON-OFF switch, and wiring. If these are okay,
contact power company.
6. If primary voltage is correct, but secondary voltage (24 v
± 10%) is incorrect, replace transformer.
7. Turn control switch to OFF position.
Step 2 — Check Processor Board Power Supply
1. Set meter to approximately 20 vdc.
2. Turn power to OFF position.
3. Connect negative lead to TP18.
4. Turn power switch to ON position and press display but-
ton to enter Quick Test mode.
5. Check voltage between TP18 and each of the following
test pins:
TEST PIN
VOLTAGE (DC)
TP3
TP4
TP6
TP10
TP14
TP15
TP7
+10
+12
+5
If a thermistor has failed or the wire is damaged, replace the
complete assembly. Do not attempt to splice the wires or repair
the assembly.
+5
+12
+12
–5*
Electronic Controls Checkout — The following will
help determine whether a processor board, a relay board, dis-
play set point board, accessory board, or 2-step demand limit
module is faulty.
*If not using a digital meter, leads must be reversed.
6. If voltage is incorrect, replace processor board.
7. Turn power to ON position.
Step 3 — Check Voltage Tolerance Circuitry
1. Turn power to OFF position.
2. Negative test probe on TP18 and system in Quick Test
mode.
3. Check voltage TP18 to TP9.
4. If voltage is greater than 11 vdc, recheck transformer in-
put voltage.
5. If transformer is okay, replace processor board.
6. Turn power to ON position.
Before checking out any board, do the following:
1. At initial start-up, enter the Quick Test mode. This test
will determine if all components are connected and oper-
ating properly.
2. If system has been operating and a malfunction occurs,
check display for diagnostic codes. Use diagnostic chart
located on inner panel of access door to control box sec-
tion of unit; this chart will help determine probable cause
of failure.
These 2 steps will help determine if a component other than
a board is at fault or if the problem is external to control circuit.
Step 4 — Check Processor Reset Line
1. Turn power to OFF position.
2. Negative probe on TP18.
A volt-ohmmeter will be needed to troubleshoot boards. A
digital meter is preferred but a Simpson 260 or equivalent will
work.
3. Check voltage TP18 to TP11.
4. If voltage is greater than +3 vdc, reset power and recheck.
5. If voltage is still incorrect, replace processor board.
6. Turn power to ON position.
To prevent damage to solid-state electronic components on
boards, meter probes should only be placed on terminals
and test points listed in following sections. Do not short the
electrical components, and use extreme care while working
on the processor board.
48
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Step 5 — Check Relay Board Outputs from the Processor
Board — This step involves checking the output signals from
relays K1-K3 on the relay board.
Table 23 on pin terminal connector J9. See Fig. 51 for J9
details.
Step 6 — Display Board Connection Checkout
1. Turn power to OFF position.
1. Turn power to OFF position.
2. Connect negative test probe to TP19 (meter still set to
dc).
3. Turn switch to ON position and enter Quick Test mode.
4. Connect positive test probe to terminal 14 on pin terminal
connector J9, and check voltage from TP19 to terminal
14 on pin terminal connector J9.
5. If not 112 ± 1 vdc, replace processor board.
6. Turn switch to OFF position.
7. Remove negative test probe from TP19. Connect positive
test probe to TP15.
8. Turn switch to ON position and go into Quick Test mode.
9. Place negative lead on terminals shown in Table 24, and
check voltage between TP15 and terminals shown in
2. Disconnect the ribbon cable.
3. Connect negative lead of meter to TP18.
4. Turn power to ON position and go into Quick Test mode.
5. Place the other lead on terminals shown in table below,
and check voltage at pin terminals on pin terminal con-
nector J10 (see Fig. 52 for pin terminal connector J10
details):
PIN TERMINAL
VOLTAGE (DC)
17
18
20*
22*
24
5
5
2.5
2.5
5
*Voltage reading is dependent on the meter’s impedance. Readings
may vary with different meters.
Fig. 51 — Relay Board Pin Terminal Connector (J9)
LEGEND
J
— Pin Terminal Strip
TP — Test Pin
Fig. 49 — Processor Board Test Points
Table 24 — Voltage Reading
J6
J5
J9 PIN NUMBERS
QUICK TEST
STEP NO.
R9
C9
R10
C10
R11
R12
C12
R13
C13
1
2
3
4
5
6
7
8
9 10 11 12 13
1.-2.3.
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
12
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
12
12
12
12
12
2.4.
2.5.
2.6.
2.7.
2.8.
2.9.
3.0.
3.1.
3.2.
3.3.
C11
0
0
0
12 0
0
0
0
0
0
12 0 12
0
0
0
0
0
12 0
12 0
12 0
12 0
12 0
12 0
12 0
0
0
0
0
0
0
0
12
0
0
0
0
0
12 12
12
0
0
0
0
0
0
0
0
0
0
12
12
12
12
12
CR9
CR10
CR11
CR12
CR13
12
0
0
0
0
0
12 0
0
0
0
0
0
0
0
0
0 12
0
0
0
0
0
0
12
0
0
NOTES:
1. Pins shown in boldface type will only be energized for 10 seconds.
All other pins will be energized continuously while at the proper
quick test step. The control will only stay in the Quick Test routine
for 10 minutes unless the display button is pressed.
2. Acceptable range for the voltage reading:
0 v — 0 to 4 v
C1
C2
C3
C4
C5
C6
C7
C8
CR1
CR2
CR3
CR4
CR5
C19
CR6
CR7
E3
CR8
12 v — 11 to 13 v
3. If any of these voltages are not measured, replace the processor
board.
K1
K2
K3
LEGEND
CR — Control Relay
J
K
— Pin Terminal Strip
— Relay
Fig. 50 — Relay Board Test Points
49
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6. If voltage is not correct, replace processor board.
Step 7 — Potentiometer Connection Checkout
1. Turn power to OFF position.
2. Remove plug connection from pin terminal strip J3.
3. Connect negative meter lead to terminal 2 of J3.
4. Turn switch to ON position and go into Quick Test mode.
Table 25 — Pin Terminal Connector J1 Voltages
PIN
TERMINAL
VOLTAGE
(vdc 0.25 v)
1
2
0
5
0
5
0
5
0
5
0
5
0
5
0
5
0
5
0
5
6
7
8
9
5. Place the other lead on terminals shown in table below,
10
11
12
13
14
15
16
17
18
19
20
21
and check voltage at pin terminals on terminal connector
J3:
PIN TERMINAL
VOLTAGE (DC)
1*
3
2.5
5
6
5
8*
2.5
2.5
5
2.5
2.5
10*
12
13*
14*
*Voltage reading is dependent on the meter’s impedance. Readings
Step 9 — Thermistor Input Connector Checkout
1. Turn power to OFF position.
2. Disconnect all plugs for pin terminal connector J2 and
mark them for later replacement.
3. Connect a negative test lead to test pin TP18.
4. Turn power to ON position, and enter the Quick Test
routine.
5. Place the other lead on terminals shown in Table 26, and
check the voltages.
6. If voltages are incorrect (per Table 26), replace processor
board.
7. Turn power to OFF position, and replace the plugs re-
moved in Step 2.
8. Turn power to ON position.
may vary with different meters.
6. If voltage is not correct, replace processor board.
Step 8 — Thermistor Input Connector Checkout
1. Turn power to OFF position.
2. Remove the thermistor connections from pin terminal
connector J1, and mark them for later replacement.
3. Connect the negative test lead to test pin TP18.
4. Turn power to ON position, and enter the Quick Test
routine.
5. Place the other lead on terminals shown in Table 25, and
check the voltages.
6. If voltages are incorrect (per Table 25), replace processor
board.
7. Turn power to OFF position, and replace the thermistor
connections removed in Step 2.
8. Turn power to ON position.
Table 26 — Pin Terminal Connector J2 Voltages
PIN
TERMINAL
VOLTAGE
(vdc 0.25 v)
1
0
5
0
5
0
5
0
5
0
5
5
5
5
5
5
5
5
5
5
2
3
4
7
8
9
10
13
14
15
17
18
19
20
21
22
23
24
If Steps 1 through 9 have been competed and the unit still
will not function properly, replace the processor board.
Fig. 52 — Display Board Pin Terminal Connector
(J10)
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RELAY BOARD TROUBLESHOOTING — The relay board
contains 13 electromechanical relays. The small relays are
24 vac, and the large relays are 115 vac. These relays are con-
trolled by the processor through the ribbon cable attached to
the relay board.
The following procedure can be used to check out the oper-
ation of the relays. To do this, turn the control ON/OFF switch
to the OFF position, and remove the wiring connectors con-
nected to pin terminal connectors J5 and J6. Set the meter for
resistance. If the contacts do not close at the required quick test
step, check the relay outputs from the processor board.
Table 28 — Terminal Strip J5 Connector
Resistance Reading
J5 PIN NUMBERS
QUICK TEST
STEP NO.
1
2
3
4
5
1. to 2.5.
2.6
2.7.
2.8.
2.9. to 3.3.
∞
0
0
0
∞
0
∞
∞
∞
∞
∞
0
0
0
0
∞
∞
0
∞
0
∞
∞
0
∞
0
LEGEND
∞ — Infinity
Relay Board Checkout (Fig. 5)
Step 1 — Low-voltage relay resistance check.
1. Turn switch to OFF position.
Step 2 — Check the Display LEDs
1. Enter Quick Test mode.
2. Remove plug connection from terminal strip J6.
2. If 88 is not displayed, replace display board.
3. Set meter to measure resistance. Connect negative test
lead to both terminals 11 and 12 of J6.
4. Turn switch to ON position and go into Quick Test mode.
Step 3 — Check Set Point Potentiometer — Advance the
display to quick test step 1.9. to determine if this potentiometer
is set and connected properly.
Step 4 — Check Display Switch — Press switch. If switch
does not click, it is faulty and the display will be energized con-
tinuously. The switch is an integral part of display board and
cannot be replaced separately.
ACCESSORY BOARD CHECKOUT — The accessory board
can be completely checked using quick test steps 2.0., 2.2., and
2.3. It can also be checked out as follows:
1. Remove the accessory board connector from the proces-
sor board and connect an ohmmeter to terminals 3 and 4
on the connector. Numbers are marked on the connector.
See Fig. 15.
2. Set the meter to 10,000 ohms. The resistance value ob-
tained should be 3,333 ohms. Adjust the potentiometers
and the resistance value should not change.
5. Place other meter lead on terminals shown in Table 27
and check resistances at each quick test step.
6. If these resistances are not correct and relay board outputs
from processor board have been checked out, replace re-
lay board.
Step 2 — High-voltage relay resistance check.
1. Turn switch to OFF position.
2. Remove plug connection from terminal connector J5.
3. Connect negative test lead to terminal 8.
4. Check the resistance between terminals 8 and 5 before
entering Quick Test mode. The resistance should be
infinity.
5. Turn switch to ON position and go into Quick Test mode.
3. Connect the ohmmeter to terminals 3 and 6. As the reset
limit potentiometer is turned clockwise, resistance should
increase from 0 to approximately 3,400 ohms.
4. Connect the ohmmeter to terminals 3 and 5. As the econ-
omizer minimum position potentiometer is turned clock-
wise, resistance should increase from 0 to approximately
3,400 ohms.
5. Connect the ohmmeter to terminals 3 and 2. As the
warm-up set point potentiometer is turned clockwise,
resistance should increase from 0 to approximately
3,400 ohms.
If any of the Steps 1 through 5 result in any other ohm read-
ing, replace the board; it cannot be serviced.
TWO-STEP DEMAND LIMIT CONTROL MODULE
(DLCM) TROUBLESHOOTING — If a problem is suspected
in the DLCM board, use the following test procedure:
The board can only be checked when it is connected to the
processor and the processor is energized so that the DLCM is
supplied with 5 vdc power. The terminals referenced are shown
in Fig. 16. Potentiometers P1 and P2 refer to the DLCM poten-
tiometers.
6. Place other meter lead on terminals shown in Table 28
and check resistance at each quick test step.
7. If these resistances are not correct and relay board outputs
from processor board have been checked per Processor
Board Checkout section on page 48, replace relay board.
DISPLAY BOARD CHECKOUT
Step 1 — Check the Output Voltage from Processor Board
to the Relay Board — Refer to Step 6 — Display Board Con-
nection Checkout section on page 49.
Table 27 — Terminal Strip J6 Connection
Resistance Reading
J6 PIN NUMBERS
QUICK TEST
STEP NO.
1. to 2.3.
2.4.
1
2
∞
∞
∞
∞
∞
∞
3
4
5
∞
∞
∞
∞
∞
∞
∞
∞
6
7
8
∞
∞
∞
∞
∞
∞
0
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
0
∞
∞
2.5.
2.6.
2.7.
2.8.
2.9.
3.0.
3.1.
3.2.
∞
0
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
∞
0
IMPORTANT: Be careful to avoid damaging the con-
nector or the processor board when taking the voltage
readings.
∞
0
∞
∞
∞
∞
∞
∞
∞
0
∞
∞
∞
0
3.3.
∞
LEGEND
∞ — Infinity
NOTE: Pins shown in boldface type will be energized for only
10 seconds. All other pins will be energized continuously while at the
proper quick test step. The control will remain in the Quick Test
mode for only 10 minutes unless the display button is pressed.
51
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Test under the following conditions:
•
•
No power to IN1 or IN2
Terminal 1 to 2 should read 4.5 vdc ±0.1 v
Terminal 2 to 3 should read 5.0 vdc ±0.1 v
Power to IN2 or to both IN1 and IN2, and P2 set at 24%
Terminal 1 to 2 should read 1.5 vdc ± 0.1 v
LIMIT SWITCHES
CAPACITOR
NOTE: Voltage should vary between 0.5 vdc and 2.5 vdc as
the setting of P2 is varied between 0% and 49%.
Terminal 2 to 3 should read 5.0 vdc ± 0.1 v
•
Power to IN1 only and P1 set at 50%
Terminal 1 to 2 should read 2.5 vdc ± 0.1 v
Terminal 2 to 3 should read 5.0 vdc ± 0.1 v
NOTE: Voltage should vary between 0.5 vdc and 2.5 vdc as
the setting of P2 is varied between 50% and 100%.
NOTE: If the voltages listed in these 3 tests are not ob-
tained during testing, the DLCM board must be replaced.
3
2
CW
ECONOMIZER
MOTOR
WINDING
(OPEN)
CCW
WINDING
(CLOSE)
T1
T2
Enthalpy Sensor Checkout — To test operation of
1
BRAKE
WINDING
1
enthalpy sensor, see Table 29.
Table 29 — Enthalpy Sensor Checkout
1
2
3
CW
EXPECTED RESULT
AND RESPONSE
TEST
Outdoor-air sensor:
Milliammeter reading should be
between 3 and 24 mA if sensor
is operating correctly. If reading
FEEDBACK
POTENTIOMETER
Enthalpy sensor + terminal
should be connected to +
terminal on motor. Connect the is 0 mA, the sensor is either
positive terminal of a DC
wired backwards or is defective.
milliammeter to the S terminal
of the sensor and the negative
terminal of the meter to SO
terminal of the enthalpy board.
BLU
RED
YEL
Indoor-air sensor:
Milliammeter reading should be
between 3 and 24 mA if sensor
is operating correctly. If reading
Enthalpy sensor + terminal
should be connected to +
AUX. SWITCH
terminal on motor. Connect the is 0 mA, the sensor is either
LEGEND
CCW — Counterclockwise
CW — Clockwise
positive terminal of a DC
wired backwards or is defective.
milliammeter to the S terminal
of the sensor and the negative
terminal of the meter to SR
terminal of the enthalpy board.
Fig. 53 — Damper Motor Connection Diagram (VAV)
Economizer Motor — All control of the motor (i.e.,
enthalpy changeover, minimum position control and mixed air
control) is accomplished from the main unit microprocessor
through a relay board. Service and installation instructions
for the unit should be consulted to verify proper operation of
these controls. The economizer motor may be checked out sep-
arately. See Fig. 52 for VAV economizer motor connection
information.
Supply Fan Variable Frequency Drive
Factory-installed optional VFD is located near the supply
fan and motor. During any service work or programming at
the VFD, operation of the fan and motor is not desirable.
Either disable the supply fan or install an accessory VFD
remote display.
Motor Test
Apply 24 volt AC power to terminals T1 and T2 of motor.
Connections to motor terminals 2 and 3 must be disconnected
NOTE: The VFDs (part no. TOSVERT130-E3) are specially
modified for use on Carrier equipment. Some specifications
and control configuration defaults for Carrier applications will
differ from the VFD manufacturer manual included in the
packet. See Table 30 for listing of Carrier-specific default
values.
A Motor Test
Jumper 1 to
replace motor.
A Expected Result and Response
Motor drives open; if not, 2 at motor
B Motor Test
Jumper 1 to
3 at motor
B Expected Result and Response
Motor drives closed; if not,
replace motor.
52
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STANDARD TRANSDUCER CONTROL — The VFD mon-
itors and controls duct pressure (DP) via a differential pressure
transducer. The pressure transducer is located in the auxiliary
control box (034-048 units) or in the supply fan compartment
(see Fig. 34). The pressure transducer’s low pressure reference
port is connected to the outside of the unit cabinet by a factory-
installed tubing section. The pressure transducer’s high pres-
sure reference point must be field-connected to the duct pres-
sure pick-up (field-supplied and installed in the supply duct).
P24
LOW LOW
RR
SI S2
S4
RCH
RES
F
R
S3
P24
ST
RX
FLB
FLA
AM CC CC
PP
IV FP
FM
FLC
4-20mA
The DP transducer monitors the static pressure in the supply
duct and provides a 4 to 20 mA signal directly to the VFD. (Re-
fer to Table 13 for transducer output signal [mA] for actual duct
static pressure.) The internal logic of the VFD compares this
signal representing actual duct pressure to the user-configured
DP set point. The VFD automatically adjusts its output to the
supply fan motor to maintain the desired DP set point. When
operating with the factory-standard DP transducer, the internal
PID logic of the VFD is enabled. EXTERNAL SIGNAL
CONTROL — If the VFD is to be controlled by an external
control system other than the factory supplied pressure trans-
ducer, the internal PID logic function of the VFD must be dis-
abled. To disable the PID control:
Fig. 54 — Supply Fan Variable Frequency Drive
Terminal Block (Size 034-048 Units)
RR
SI S2
S4
RCH
RES
F
R
S3
P24
LOW LOW
P24
ST
RX
FLB
FLA
AM CC CC
PP
IV FP
FM
FLC
1. Disconnect and lock out all power to the Carrier rooftop
unit.
2. Remove the VFD access cover.
4-20mA
Fig. 55 — Supply Fan Variable Frequency Drive
Terminal Block (Size 054-104 Units)
Ensure the “CHARGE” lamp on the VFD is unlit. This
may up to 4 minutes. The “CHARGE” lamp indicates that
the main capacitors in the VFD are charged. Internal com-
ponents of the VFD should not be touched until the
“CHARGE” lamp is completely out. Electrical shock can
cause injury or death.
VFD OPERATION — When troubleshooting the VFD, check
first that all required conditions for VFD operation are
satisfied.
For the VFD to run, the following conditions must be met at
the VFD:
1. Drive enable jumper is installed from terminals CC-ST
(factory supplied) (see Fig. 54 and 55).
2. Proper rotation jumper is installed at terminals R-CC (re-
verse rotation, factory supplied) or terminals F-CC (for-
ward rotation, factory supplied).
3. Install a jumper across S2-CC (see Fig. 54 and 55 for
VFD terminal board connections).
4. Remove factory-supplied cable attached to IV and CC.
5. Remove other end of the same cable from the pressure
sensor.
6. Connect field supplied speed reference (4 to 20 mA)
across terminals IV-CC.
UNIT SIZES
ROTATION
JUMPER
034-048
054-074
078-104
Reverse
Forward
Forward
R-CC
F-CC
F-CC
7. Disable the supply fan motor operation.
8. Reconnect power to the unit and VFD.
9. Reprogram the VFD to accept an external reference (in
the Utility parameters group [Gr.Ut], set parameter item
Fnod [no.312] = 4).
3. Emergency stop jumper is installed from terminals
S4-CC (factory supplied).
4. A 4 to 20 mA signal is applied across terminals IV-CC
(from pressure transducer, factory supplied).
10. Enable supply fan motor and return power to the unit.
SUPPLY FAN MOTOR OVERLOAD PROTECTION — The
VFD provides operating overload protection for the supply fan
motor. The factory has programmed the VFD overload func-
tion to match the factory-installed motor (motor size and effi-
ciency). If the supply fan motor is changed from the original
factory selection, the overload value may need to be changed
by the service person. Contact your local Carrier representative
for assistance in determining the proper overload setting.
5. DIP switch SW1 (located on the VFD’s printed circuit
control panel) must be set to ‘‘I’’ (indicating usage of a 4
to 20 mA input signal at terminals ‘‘IV’’).
6. Speed Control (located on the VFD’s keypad/display) set
for ‘‘Remote’’ (press the ‘‘Speed Ctrl’’ button until LED
‘‘Remote’’ is illuminated).
7. Programmed according to Carrier defaults.
8. Duct Pressure set point established by user, or use factory
default (30 Hz indicating 2.50-in. wg) (see Table 13).
NOTE: Variable frequency drive size is matched to factory-
installed motor size. Do not increase motor size without also
changing to equivalent VFD size.
53
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Table 30 — Carrier Default Program Parameter Values (Supply Fan VFD)
PARAMETER GROUP
PARAMETER
ACC1
DEC1
UL
DEFAULT VALUE
60.0 Sec
60.0 Sec
60.0 Hz
LL
10.0 Hz*
Luln
P3
1
20%
F-P3
P4
0.0 Hz
100%
SEtP
(Setup)
F-P4
tHr1
StC1
StL1
OLN
tYP
60 Hz
See Table 32
0
110%
1
5*
FH
Pt
60 Hz
2
Gr.F
(Fundamental)
FbP1
Fbln
GP
1*
2
.30
Gl
2 sec
GA
0
80
10
1
Gr.Fb
(Feedback)
GFS
P1LL
PuL
PuUl
PuLL
Fsor
Sr.n
SrN1
10
10
60 Hz
Gr.SF
(Frequency Settings)
1* (054-104 only)
0* (054-104 only)
Gr.Pn
(Panel Control)
Fr
0*
1t
1
1t0
0
1t1
1t2
56
13
Gr.St
(Terminal Selection)
1t3
3
1t4
10
UuC
UuCt
ArSt
Cnod
bLSF
Fnod
bLPn
1*
2
3
1*
Gr.Pr
(Protection)
1* (054-104 only)
Gr.Ut
(Utility)
2*
1*
*These settings differ from the Toshiba defaults and are required for Carrier applications.
NOTE: To restore original factory settings, change tYP to 6 in Setup mode (SEtP). This restores the VFD original factory settings.
54
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VFD OPERATIONAL STATUS — The VFDs contain ex-
tensive self-diagnostic functions which are accessed through
the VFD display panel (located on the front of the VFD or at a
remote location when the accessory remote display package
has been installed).
logic of the power exhaust VFD compares this signal repre-
senting actual duct pressure to the user-configured BP set
point. The power exhaust VFD automatically adjusts its output
to the power exhaust fan motor to maintain the desired BP set
point. When operating with the factory-standard BP transducer,
the internal PID logic of the power exhaust VFD is enabled.
EXTERNAL SIGNAL CONTROL — If the power exhaust
VFD is to be controlled by an external control system other
than the factory-supplied pressure transducer, the internal PID
logic function of the power exhaust VFD must be disabled. To
disable the PID control:
1. Disconnect and lock out all power to the Carrier rooftop
unit.
If using the VFD display panel, disconnect all power to
the unit and the VFD before entering unit, or use the
accessory remote display module. Disable supply fan and
motor operation before accessing VFD-mounted display
module.
When power is first supplied to the VFD, the display auto-
matically starts with the frequency monitor function of its stan-
dard monitor mode. In the frequency monitor function, the out-
put frequency is displayed. Push the S/P/M (Setup/ Program/
Monitor) key to switch to the Mode Selection menu. Push the
S/P/M key again to toggle the display back to the standard
monitor mode.
From the Mode Selection menu, the service person can
view all of the monitored status variables, including up to four
user-selected variables and any trip history in the memory.
2. Remove the VFD access cover.
Ensure the “CHARGE” lamp on the VFD is unlit. This
may up to 4 minutes. The “CHARGE” lamp indicates that
the main capacitors in the VFD are charged. Internal com-
ponents of the VFD should not be touched until the
“CHARGE” lamp is completely out. Electrical shock can
cause injury or death.
Refer to the separate VFD Operation Manual for detailed
instructions on accessing diagnostic information, initiating
troubleshooting, and clearing any trip history.
RESTORING FACTORY VFD DEFAULTS — The original
factory configuration values are saved in the memory of the
VFD and can be restored by the service person if required.
There are two types of saved file data: Carrier-factory settings
(factory programmed settings made to the VFD which apply
specifically to the unit it is installed on) and standard defaults
for general Carrier unit use.
The Carrier-factory settings are maintained as user settings.
These can be restored by entering the Setup mode (in the
S/P/M menu) and setting parameter tYP = 6 on the keypad/
display. This will recall the specific factory defaults for this
unit.
3. Install a jumper across S2-CC (see Fig. 56 for power ex-
haust VFD terminal board connections).
4. Remove factory-supplied cable attached to IV and CC.
5. Remove other end of the same cable from the pressure
sensor.
6. Connect field-supplied speed reference (4 to 20 mA)
across terminals IV-P24.
7. Disable the supply fan motor operation.
8. Reconnect power to the unit and power exhaust VFD.
9. Reprogram the power exhaust VFD to accept an external
reference (in the Utility parameters group [GR.Ut], set
parameter item Fnod [no.312] = 4).
10. Enable supply fan motor and return power to the unit.
Occasionally it may be necessary to restore the VFD de-
faults to the general Carrier use values. These are stored in an
OPTION ROM (read-only memory chip). However, some
variables may need to be manually changed to match the spe-
cific unit’s factory default settings. To recall the general Carrier
defaults, enter the Setup mode and set parameter tYP = 3. Re-
fer to Table 31 for items requiring manual adjustment.
Table 31 — Supply Fan VFD Required
User Adjusted Defaults
SIZES
All
ITEM
Motor overload settings (see Table 32)
1. Check jumper CC-F
2. Gr.UT/bLSF = 1
054-104
3. Gr.SF/Sr.n = 1
Power Exhaust Variable Frequency Drive
(48FM and 50FM,FS)
4. Gr.SF/SrN1 = 0
5. SEtP/tYP = 5 (Save User Settings)
NOTE: The VFDs (part no. TOSVERT130-E3) are specially
modified for use on Carrier equipment. Some specifications
and control configuration defaults for Carrier applications
will differ from the VFD manufacturer manual included in the
packet. See Table 33 for listing of Carrier-specific default
values.
Table 32 — Supply Fan Motor Overload Settings
UNIT
IFM HP
DESIGNATION
VOLTAGE
tHr1
SETTING
DESIGNATION
UNIT 48/50
AND
Model No.
Position 12
Model No.
Position 15
STANDARD TRANSDUCER CONTROL — The VFD
monitors and controls building pressure (BP) via a differential
pressure transducer. The pressure transducer is located in the
auxiliary control box. The pressure transducer’s high-pressure
reference port is connected to the outside of the unit cabinet by
a factory-installed tubing section. The pressure transducer’s
low-pressure reference point must be field-connected to the
building pressure pick-up (field-supplied and installed in the
building).
The BP transducer monitors the static pressure in the occu-
pied space and provides a 4 to 20 mA signal directly to the
power exhaust VFD. (Refer to Table 30 for transducer output
signal [mA] for actual building static pressure.) The internal
5
5
6
6
6
6
6
And
And
And
And
And
And
And
N
Q
A
K
Q
Q
T
82.0
86.0
80.0
80.0
80.0
80.0
78.0
FK,FY,
JK,JY
FKX,FKY,
JKX,JKY
LEGEND
IFM — Indoor Fan Motor
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POWER EXHAUST FAN MOTOR NO. 1 OVERLOAD
PROTECTION — The VFD provides operating overload
protection for the supply fan motor. The factory has pro-
grammed the power exhaust VFD overload function to match
the factory-installed motor (motor size and efficiency). If the
power exhaust fan motor is changed from the original factory
selection, the overload value may need to be changed by the
service person. Contact your local Carrier representative for
assistance in determining the proper overload setting.
P24
LOW LOW
RR
SI S2
S4
RCH
RES
F
R
S3
P24
ST
C
A
RX
FLB
FLA
AM CC CC
PP
IV FP
FM
FLC
NOTE: Variable frequency drive size is matched to factory-
installed motor size. Do not increase motor size without also
changing to equivalent VFD size.
4-20mA
Fig. 56 — Variable Frequency Drive Terminal Block
Table 33 — Carrier Power Exhaust VFD Default Program Parameter Values
PARAMETER GROUP
PARAMETER
DEFAULT VALUE
ACC1
DEC1
UL
60.0 Sec
60.0 Sec
59.8 Hz
LL
10.0 Hz*
Luln
P3
1
20%
F-P3
P4
0.0 Hz
98%
SEtP
(Setup)
F-P4
tHr1
StC1
StL1
OLN
tYP
60 Hz
See Table 35
0
110%
1
5*
FH
Pt
60 Hz
12
Gr.F
(Fundamental)
FbP1
Fbin
GP
Gl
GA
1*
2
.30
2 sec
0
Gr.Fb
(Feedback)
GFS
P1LL
PuL
PuUl
PuLL
80
10
1
10
10
Gr.SF
Fsor
Fr
60 Hz
0*
(Frequency Settings)
Gr.Pn
(Panel Control)
1t
1t0
1
0
1t1
1t2
1t3
56
13
3
Gr.St
1t4
Ot1
Ot2
10
4*
2*
5*
100*
15*
1*
2
(Terminal Selection)
Ot2d
Ot2H
LF
UuC
UuCt
ArSt
Cnod
Fnod
bLPn
Gr.Pr
(Protection)
3
1*
2*
1*
Gr.Ut
(Utility)
*These settings differ from the Toshiba defaults and are required for Carrier applications.
NOTE: To restore original factory settings, change tYP to 6 in SEtup mode (SEtP).
This restores the VFD original factory settings.
56
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POWER EXHAUST VFD OPERATION — When trouble-
shooting the power exhaust VFD, check first that all required
conditions for power exhaust VFD operation are satisfied.
Refer to the separate VFD Operation Manual for detailed
instructions on accessing diagnostic information, initiating
troubleshooting, and clearing any trip history.
For the power exhaust VFD to run, the following conditions
must be met at the power exhaust VFD:
1. Drive enable jumper is installed from terminals ST-CC
(factory supplied) (see Fig. 56).
2. Proper rotation jumper is installed at terminals R-CC (re-
verse rotation, factory supplied).
3. Emergency stop jumper is installed from terminals
S4-CC (factory supplied).
RESTORING FACTORY POWER EXHAUST VFD
DEFAULTS — The original factory configuration values are
saved in the memory of the power exhaust VFD and can be
restored by the service person if required. There are two types
of saved file data: Carrier-factory settings (factory pro-
grammed settings made to the power exhaust VFD which
apply specifically to the unit it is installed on) and standard
defaults for general Carrier unit use.
The Carrier-factory settings are maintained as user settings.
These can be restored by entering the Setup mode (in the
S/P/M menu) and setting parameter tYP = 6 on the keypad/dis-
play. This will recall the specific factory defaults for this unit.
Occasionally it may be necessary to restore the power ex-
haust VFD defaults to the general Carrier use values. These are
stored in an OPTION ROM (read-only memory chip). Howev-
er, some variables may need to be manually changed to match
the specific unit’s factory default settings. To recall the general
Carrier defaults, enter the Setup mode and set parameter
tYP = 3. Refer to Tables 34 and 35 for items requiring manual
adjustment.
4. A 4 to 20 mA signal is applied across terminals IV-P24
(from pressure transducer, factory supplied).
5. DIP switch SW1 (located on the VFD’s printed circuit
control panel) must be set to “I” (indicating usage of a 4
to 20 mA input signal at terminals “IV”).
6. Speed Control (located on the VFD’s keypad/display) set
for “Remote” (press the “Speed Ctrl” button until LED
“Remote” is illuminated).
7. Programmed according to Carrier defaults.
8. Building Pressure set point established by user, or
use factory default (30 Hz indicating 0.0 in. wg) (see
Table 15).
POWER EXHAUST VFD OPERATIONAL STATUS —
The power exhaust VFDs contain extensive self-diagnostic
functions which are accessed through the power exhaust VFD
display panel (located on the front of the power exhaust VFD
or at a remote location when the accessory remote display
package has been installed.)
Table 34 — Power Exhaust VFD Required
User Adjusted Defaults
UNIT
ALL
ITEM
Motor Overload Settings (See Table 35)
Gr.St/Ot1 = 4
Gr.St/Ot2 = 2
Gr.St/Ot2d = 5
Gr.St/Ot2H = 100
Gr.St/LF = 15
If using the VFD display panel, disconnect all power to
the unit and the VFD before entering unit, or use the
accessory remote display module. Disable supply fan and
motor operation before accessing VFD-mounted display
module.
SEtP/UL = 59.8
SEtP/P4 = 98
Table 35 — Power Exhaust Motor
Overload Settings
When power is first supplied to the power exhaust VFD, the
display automatically starts with the frequency monitor func-
tion of its standard monitor mode. In the frequency monitor
function, the output frequency is displayed. Push the S/P/M
(Setup/Program/Monitor) key to switch to the Mode Selec-
tion menu. Push the S/P/M key again to toggle the display
back to the standard monitor mode.
From the Mode Selection menu, the service person can
view all of the monitored status variables, including up to four
user-selected variables and any trip history in the memory.
MODEL NUMBER
POSITION 16
TOTAL
HP
MOTOR HP
(ea)
tHr1
SETTING
H, T
J, V
K, W
L, X
M, Y
20
30
40
50
60
10
15
20
25
30
97.3
100.0
100.0
93.5
92.3
Unit Wiring — A typical wiring schematic is shown in
Fig. 57.
57
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LEGEND AND NOTES FOR FIG. 57
ALM
C
— Alarm
IGVM — Inlet Guide Vanes Motor
— Contactor
LAT
LPS
— Leaving-Air Temperature
— Low-Pressure Switch
CB
— Circuit Breaker
— Control Circuit Breaker
CCB
MTR — Motor
COMP — Compressor
MV
NC
NO
— Main Valve
— Normally Closed
— Normally Open
CH
CR
— Crankcase Heater
— Control Relay
DPS
DPT
EAT
EC
— Differential Pressure Switch
— Discharge Pressure Transducer
— Enering-Air Temperature
— Enthalpy Control
OFC — Outdoor Fan Contactor
OFM — Outdoor (Condenser) Fan Motor
OMR — Outdoor Motor Relay
PCB — Power Exhaust Circuit Breaker
PEC — Power Exhaust Contactor
PEDM — Power Exhaust Damper Motor
PEM — Power Exhaust Motor
P, PL — Plug
ECR
EOR
— Economizer Close Relay
— Economizer Open Relay
EQUIP — Equipment
FS
— Fan Status Switch
GND — Ground
RCB — Return Fan Circuit Breaker
RES — Resistor
HIR
HPS
HR
HTR
IDC
IDM
IFC
— Heat Interlock Relay
— High-Pressure Switch
— Heater Relay
RFC — Return Fan Contactror
RFM — Return Fan Motor
SCT — Saturated Condensing Thermistor
— Heater
— Induced Draft Contactor
— Induced Draft Motor
— Indoor (Evaporator) Fan Contactor
TB
— Terminal Block
TRAN — Transformer
U
— Unloader
IFCB — Indoor Fan Circuit Breaker
IFM
IGV
VFD — Variable Frequence Drive
Field Wiring
— Indoor Fan Motor
— Inlet Guide Vanes
Factory Wiring
NOTES:
1.Connect TRAN1 to
H4
H3
for 460 v units. Connect to
for 230 v
units. If 208/230 v units are run with a 208 v power supply con-
H2
nect to
.
2.Connect TRAN2 to BLK lead for 460 v units. Connect to ORN
lead for 230 v units. If 208/230 v units are run with a 208 v
power supply connect to RED lead.
3.Circuit breaker must trip amps are equal to or less than 156%
FLA (full load amps) for CB1 and CB2. All others are 140%.
4.If any of the original wire furnished must be replaced, it must
be replaced with type 90° C wire or its equivalent.
5.Number(s) indicates the line location of contacts. A bracket
over (2) numbers signifies single pole double throw contacts.
An underlined number signifies a normally closed contact.
Plain numbers (no lines), signify a normally opened contact.
6.Condenser fan motors are thermally protected.
7.Three phase motors are protected under primary single phas-
ing conditions.
58
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60
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SERVICE TRAINING
Packaged Service Training programs are an excellent way to increase your knowledge of the equip-
ment discussed in this manual, including:
• Unit Familiarization
• Installation Overview
• Maintenance
• Operating Sequence
A large selection of product, theory, and skills programs are available, using popular video-based for-
mats and materials. All include video and/or slides, plus companion book.
Classroom Service Training which includes ‘‘hands-on’’ experience with the products in our labs can
mean increased confidence that really pays dividends in faster troubleshooting and fewer callbacks.
Course descriptions and schedules are in our catalog.
CALL FOR FREE CATALOG 1-800-962-9212
[ ] Packaged Service Training
[ ] Classroom Service Training
Copyright 2000 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 534-763 Printed in U.S.A. Form 48/50F,J-3T Pg 62 3-00 Replaces: 48/50F,J-1T
Book 1
1
Tab 1a 1b
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START-UP CHECKLIST
MODEL NO.: _____________________________________
SERIAL NO.: ______________________________________
TECHNICIAN:_____________________________________
DATE: ___________________________________________
I. PRE-START-UP:
VERIFY THAT UNIT IS LEVEL
VERIFY THAT ALL PACKING MATERIALS HAVE BEEN REMOVED FROM UNIT
LOOSEN ALL SHIPPING HOLDDOWN BOLTS AND REMOVE SHIPPING BRACKETS PER INSTRUCTIONS
VERIFY THAT COMPRESSOR SUSPENSION SPRINGS HAVE BEEN LOOSENED PER INSTRUCTIONS
VERIFY OPENING OF ECONOMIZER HOODS
VERIFY INSTALLATION OF EXHAUST HOODS
CONFIRM THAT TUBING FOR SPACE AND SUPPLY DUCT PRESSURES HAS BEEN INSTALLED
VERIFY THAT CONDENSATE CONNECTION IS INSTALLED PER INSTRUCTIONS
VERIFY THAT POWER SUPPLY MATCHES UNIT DATA PLATE
VERIFY THAT ALL ELECTRICAL CONNECTIONS AND TERMINALS ARE TIGHT
CHECK GAS PIPING FOR LEAKS (48FK,JK ONLY)
CHECK THAT INDOOR-AIR FILTERS ARE CLEAN AND IN PLACE
CHECK FAN WHEEL AND PROPELLER FOR LOCATION IN HOUSING/ORIFICE, AND VERIFY SET SCREWS ARE
TIGHT
VERIFY THAT FAN SHEAVES ARE ALIGNED AND BELTS ARE PROPERLY TENSIONED
OPEN SUCTION, DISCHARGE, AND LIQUID LINE SERVICE VALVES
CHECK COMPRESSOR OIL LEVEL SIGHT GLASS AND VERIFY PROPER LEVEL
VERIFY THAT CRANKCASE HEATERS HAVE BEEN ENERGIZED FOR 24 HOURS
CHECK VOLTAGE IMBALANCE
LINE-TO-LINE VOLTS:
(AB + AC + BC)/3 = AVERAGE VOLTAGE =
MAXIMUM DEVIATION FROM AVERAGE VOLTAGE =
AB
V
AC
V
BC
V
V
V
VOLTAGE IMBALANCE = 100 X (MAX DEVIATION)/(AVERAGE VOLTAGE) =
%
IF OVER 2% VOLTAGE IMBALANCE, DO NOT ATTEMPT TO START SYSTEM!
CALL LOCAL POWER COMPANY FOR ASSISTANCE.
II. PRELIMINARY CHECKLIST ITEMS:
CONTROL SETTINGS
DIP SWITCHES SET TO MATCH INSTALLED ACCESSORIES:
SUPPLY AIR SET POINT RESET (DIP SWITCH NO. 4 ON)
MORNING WARM-UP (DIP SWITCH NO. 4 ON)
DEMAND LIMIT (DIP SWITCH NO. 5 ON)
SUPPLY AIR SET POINT (P1) SET BETWEEN 45 AND 70 F
ECONOMIZER MINIMUM POSITION (P5) SET PER PLANS
SUPPLY AIR SET POINT RESET SETTINGS:
RESET INITIATION TEMPERATURE (P7) (TYPICALLY 68 TO 72 F)
RESET LIMIT TEMPERATURE (P3) (TYPICALLY 60 TO 70 F)
MORNING WARM-UP TEMPERATURE (TYPICALLY 50 TO 65 F)
IGV/VFD DUCT PRESSURE SET POINT PER PLANS
BUILDING PRESSURE (MODULATING POWER EXHAUST) SET PER PLANS
DEMAND LIMIT SETTINGS PER PLAN:
SINGLE STEP DEMAND LIMIT (P4) SET (TYPICALLY 25 TO 50%)
TWO-STEP DEMAND LIMIT
DLCM-P1 SET (TYPICALLY 50 TO 75%)
DLCM-P2 SET (TYPICALLY 0 TO 25%)
OCCUPIED/UNOCCUPIED SWITCH INSTALLED PER FIG. 23 (CLOSE TO START UNIT)
CL-1
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III. START-UP
CHECK EVAPORATOR FAN SPEED AND RECORD.
CHECK CONDENSER FAN SPEED AND RECORD.
AFTER AT LEAST 10 MINUTES RUNNING TIME, RECORD THE FOLLOWING MEASUREMENTS:
COMP A1
COMP A2
COMP B1
COMP B2
OIL PRESSURE
SUCTION PRESSURE
SUCTION LINE TEMP
DISCHARGE PRESSURE
DISCHARGE LINE TEMP
ENTERING CONDENSER AIR TEMP
LEAVING CONDENSER AIR TEMP
EVAP ENTERING AIR DB TEMP
EVAP ENTERING AIR WB TEMP
EVAP LEAVING AIR DB TEMP
EVAP LEAVING AIR WB TEMP
COMPRESSOR AMPS (L1)
COMPRESSOR AMPS (L2)
COMPRESSOR AMPS (L3)
ELECTRICAL
SUPPLY FAN AMPS
EXHAUST FAN AMPS
L2
ELECTRIC HEAT AMPS L1
TEMPERATURES
L3
(50 SERIES UNITS ONLY)
OUTDOOR-AIR TEMPERATURE
RETURN-AIR TEMPERATURE
COOLING SUPPLY AIR
PRESSURES
F
F
F
DB (Dry-Bulb)
DB
F WB (Wet-Bulb)
GAS INLET PRESSURE
IN. WG (48 SERIES UNITS ONLY)
GAS MANIFOLD PRESSURE STAGE NO. 1
UNITS ONLY)
IN. WG
STAGE NO. 2
IN. WG (48 SERIES
REFRIGERANT SUCTION
CIRCUIT NO. 1
PSIG
PSIG
CIRCUIT NO. 2
CIRCUIT NO. 2
PSIG
PSIG
REFRIGERANT DISCHARGE CIRCUIT NO. 1
VERIFY REFRIGERANT CHARGE USING CHARGING CHARTS IN UNIT INSTALLATION INSTRUCTIONS
GENERAL
ECONOMIZER MINIMUM VENT SETTING TO JOB REQUIREMENTS
IV. NOTES
Copyright 2000 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book
Tab
1
1
PC 111
Catalog No. 534-763
Printed in U.S.A.
Form 48/50F,J-3T
Pg CL-2
3-00
Replaces: 48/50F,J-1T
1a 1b
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