Bryant R 22 User Manual

Application Guide and

Service Manual

AIR CONDITIONERS AND HEAT PUMPS

USING R-22 REFRIGERANT

Cancels: AP01-3, SM01,02-4

SM01,02-5

10-00

NOTE: Read the entire instruction manual before starting the

installation.

Fan Motors..............................................................................21

Service Alarm Control Board.................................................21

Outdoor Thermostat(s)............................................................22

Compressor Plug.....................................................................24

Low-Voltage Terminals..........................................................25

This symbol → indicates a change since the last issue.

TABLE OF CONTENTS

RECIPROCATING COMPRESSOR ..........................................25

Mechanical Failures................................................................25

Electrical Failures ...................................................................26

System Cleanup After Burnout ..............................................27

Compressor Removal And Replacement ...............................27

SAFETY CONSIDERATIONS.....................................................1

INTRODUCTION..........................................................................2

INSTALLATION GUIDELINE ....................................................2

Residential New Construction..................................................2

Add-On Replacement (Retrofit)...............................................2

Seacoast (For Air Conditioners Only) .....................................2

COPELAND SCROLL COMPRESSOR ....................................28

Features ...................................................................................28

Troubleshooting ......................................................................28

Discharge Thermostat.............................................................28

Discharge Solenoid Valve ......................................................28

ACCESSORY DESCRIPTIONS...................................................2

Compressor Crankcase Heater..................................................2

Evaporator Freeze Thermostat..................................................2

Winter Start Control .................................................................2

Compressor Start Assist—PTC ................................................2

Compressor Start Assist Capacitor/Relay ................................2

Low-Ambient Controller ..........................................................2

MotorMaster™ Control ............................................................2

Low-Ambient Pressure Switch.................................................2

Wind Baffle...............................................................................3

Coastal Filter.............................................................................3

Support Feet..............................................................................3

Liquid-Line Solenoid Valve.....................................................3

Thermostatic-Expansion Valve.................................................3

Isolation Relay ..........................................................................3

MILLENNIUM SCROLL COMPRESSOR................................29

Features ...................................................................................29

Compressor Protection............................................................29

Troubleshooting ......................................................................29

Scroll Compressor, 3–Phase Monitor.....................................29

TWO-SPEED SYSTEM ..............................................................29

Cautions and Warnings...........................................................29

System Functions....................................................................29

Factory Defaults......................................................................33

Major Components..................................................................33

LED Function/Malfunction Lights.........................................34

Troubleshooting ......................................................................34

LOW-AMBIENT GUIDELINE.....................................................3

REFRIGERATION SYSTEM .....................................................35

Refrigeration Cycle.................................................................35

Leak Detection........................................................................35

Brazing ....................................................................................37

Service Valves ........................................................................38

Check-Flo-Rater™ (Bypass-Type) Heat Pumps Only...........39

Reversing Valve......................................................................39

Thermostatic-Expansion Valves (TXV).................................40

Thermostatic-Expansion Valve (Bi-Flow TXV)....................41

Coil Removal ..........................................................................41

Liquid-Line Strainer (Heat Pumps Only) ..............................41

Accumulator............................................................................43

Contaminant Removal ............................................................43

System Charging.....................................................................43

Checking Charge.....................................................................43

LONG-LINE GUIDELINE............................................................3

Approved Systems ....................................................................3

Interconnecting Tubing Sizing .................................................3

Metering Device Sizing............................................................6

Liquid-Line Solenoid And Tubing Configuration...................7

Charging Information................................................................8

2–Speed Applications ...............................................................8

UNIT IDENTIFICATION .............................................................8

Product Number Stamped on Unit-Rating Plate......................8

Serial Number Identification ....................................................9

CABINET.....................................................................................10

Remove Top Cover—Before 1/1/92 ......................................10

Remove Fan-Motor Assembly—Before 1/1/92.....................10

Information Plate—Reliant Products......................................10

Control-Box Cover—Cube Products......................................10

Remove Top Cover— After 1/1/92 .......................................10

Remove Fan-Motor Assembly—After 1/1/92........................11

CARE AND MAINTENANCE...................................................45

SAFETY CONSIDERATIONS

Service and repair of these units should be attempted only by

trained service technicians familiar with Bryant standard service

instructions and training manual.

ELECTRICAL..............................................................................12

Aluminum Wire ......................................................................12

Contactors................................................................................13

Capacitors................................................................................14

Cycle Protector........................................................................15

Crankcase Heater ....................................................................16

Time-Delay Relay...................................................................16

Pressure Switches....................................................................17

Defrost Thermostats................................................................18

Defrost-Control Board ............................................................18

All equipment should be installed in accordance with accepted

practices and unit Installation Instructions, and in compliance with

all national and local codes.

Power should be turned off when servicing or repairing electrical

components. Extreme caution should be observed when trouble-

shooting electrical components with power on. Observe all warn-

ing notices posted on equipment.

—1—

TABLE 1—REQUIRED FIELD-INSTALLED ACCESSORIES FOR AIR CONDITIONERS AND HEAT PUMPS

REQUIRED FOR

LOW-AMBIENT

APPLICATIONS

(BELOW 55°F)

REQUIRED FOR

LONG-LINE

APPLICATIONS*

(OVER 50 FT)

REQUIRED FOR

SEA COAST

APPLICATIONS

(WITHIN 2 MILES)

ACCESSORY

Crankcase Heater

Evaporator Freeze Thermostat

Winter Start Control

Accumulator

Yes

Yes†

Yes

Compressor Start Assist

Capacitor and Relay

Yes

Low Ambient Controller,

MotorMaster™ Control,

Yes

Low-Ambient Pressure Switch

Wind Baffle

Coastal Filter

Support Feet

See Low-Ambient Instructions

Yes

Recommended

Liquid-Line Solenoid Valve

See Long-Line

Application

Guideline

Hard-Shutoff TXV

Ball-Bearing Fan Motor

Isolation Relay

Yes‡

Yes**

*For tubing line sets between 50 and 175 ft, refer to Residential Split-System Long-Line Application Guideline.

†Only when low-pressure switch is used.

‡Required for Low-Ambient Controller (full modulation feature) and MotorMaster™ control only.

** Required on Heat Pumps only.

IX. WIND BAFFLE

LONG-LINE GUIDELINE

A field-fabricated sheet-metal cover used to stop prevailing winds

or where outdoor ambient temperature is less than 55°F during unit

operation of cooling mode.

This Long-Line Application Guideline applies to all Bryant

residential air conditioner and heat pump split systems that have a

nominal capacity of 18,000 to 60,000 Btuh. This guideline

provides required system changes and accessories necessary for

any residential product having piping requirements greater than 50

ft or installations where indoor unit is located above outdoor unit.

This guideline is intended to cover applications outside the

standard Installation Instructions. This guideline is for standard,

single-speed products. For applications involving 2-speed prod-

ucts, refer to Section VI first.

X. COASTAL FILTER

A mesh screen inserted under top cover and inside base pan to

protect condenser coil from salt damage without restricting air-

flow.

XI. SUPPORT FEET

Four adhesive plastic feet which raise unit 4 in. above mounting

pad. This allows sand, dirt, and other debris to be flushed from unit

base; minimizes corrosion.

NOTE: The presale literature for outdoor unit must be referred to

in conjunction with this guideline.

XII. LIQUID-LINE SOLENOID VALVE

I. APPROVED SYSTEMS

An electrically operated shutoff valve to be installed at outdoor or

indoor unit (depending on tubing configuration) which stops and

starts refrigerant liquid flow in response to compressor operation.

Maintains a column of refrigerant liquid ready for action at next

compressor-operation cycle and prevents liquid migration during

the off cycle.

Any residential indoor/outdoor unit combination listed in the

outdoor unit presale literature is an approved system, EXCEPT the

following:

•

Indoor coils with capillary-metering devices

All equipment less than nominal 18,000 Btuh

All 1/4-in. and 5/16–in. liquid-line applications

XIII. THERMOSTATIC-EXPANSION VALVE

Any indoor furnace coil/fan coil not listed in outdoor unit

A modulating flow-control device which meters refrigerant flow

rate into the evaporator in response to the superheat of the

refrigerant gas leaving the evaporator. Only use factory-specified

TXV’s.

presale literature

•

Any application which has interconnecting tubing with an

equivalent length greater than 175 ft

XIV. ISOLATION RELAY

II. INTERCONNECTING TUBING SIZING

A DPDT relay which switches the low-ambient controller out of

the outdoor fan-motor circuit when the heat pump switches to

heating mode.

Table 4 lists recommended interconnecting vapor-line diameters

for equivalent total-line lengths. All residential split systems

installed in long-line applications must use only 3/8-in. liquid

lines. Equivalent line length equals the linear length (measured) of

interconnecting vapor tubing plus losses due to elbows. (See Table

5 and Fig. 3.) Liquid lines larger than 3/8-in. OD greatly increase

charge quantity of the system. Excessive charge increases risk of

migration and compressor damage. Table 4 provides the estimated

percentage of nominal cooling-capacity losses based on the stan-

dard, required vapor line size versus what is selected for the

long-line application. Since the vapor line is the discharge line in

heating mode, losses are minimal.

LOW-AMBIENT GUIDELINE

The minimum operating temperature for these units in cooling

mode is 55°F outdoor ambient without additional accessories. This

equipment may be operated in cooling mode at ambient tempera-

tures below 55°F when the accessories listed in Table 1 are

installed. Wind baffles are required when operating in cooling

mode at ambients below 55°F. Refer to Fig. 1 or 2 and Table 2 or

3 for wind baffle construction details.

—3—

/ ″ x / ″ (5.56 x 9.53) SLOT

4 REQ'D

/ ″ (3.45) DIA HOLE

2 REQ'D

/ ″

5 ⁵

(151.5)

″

(9.6)

/ ″ (5.56) DIA HOLE 2 REQ'D

/ ″

(12.7)

TYP

SUPPORT

MAT'L: 18 GA STEEL

″

(11.6)

¹/₂″

(12.7)

/ ″ (3.45) DIA HOLE

1 REQ'D

″

(11.6)

/ ″ (5.56) DIA HOLE

3 REQ'D

/ ″

6″

(152.4)

/ ″ (9.6)

(6.3)

/ ″ x 2″

BAFFLE

MAT'L: 20 GA STEEL

(5.56 x 50.8) SLOT

SCREW

10 REQ'D

SUPPORT

4 REQ'D

OUTDOOR

UNIT

BAFFLE

2 REQ'D

BAFFLE ASSEMBLY

A95445

Fig. 1—Wind Baffle Construction for Reliant Units

—4—

Calculate the linear length of vapor tube required, adding any

losses for the total number of elbows for application. (See Table

5.) Using this equivalent length, select desired vapor-line size from

Table 4. Subtract the nominal percentage loss from outdoor-unit

presale-literature Detailed Cooling Capacities data for the given

indoor/outdoor combination. Reference all notes of Table 4.

All standard accessory-tubing kits are supplied with 3/8-in. insu-

lation on vapor line.

For minimal capacity loss in long-line application, 1/2-in. insula-

tion should be specified.

NOTE: When specifying vapor-line insulation, be aware of the

following standard practice:

TABLE 2—WIND BAFFLE DIMENSIONS FOR RELIANT UNITS WITH AEROQUIET-SYSTEM TOP (IN.)

UNIT SIZE

Small

UNIT HEIGHT

23-13/16

27-13/16

33-13/16

27-13/16

33-13/16

39-13/16

33-13/16

39-13/16

17-1/4 24-5/16 10-1/4 19-3/4 20-1/2 34-1/2 19-5/8 20-3/8 19-5/8

17-1/4 24-5/16 10-1/4 23-3/4 24-1/2 34-1/2 23-5/8 24-3/8 23-5/8

17-1/4 24-5/16 10-1/4 29-3/4 30-1/2 34-1/2 29-5/8 30-3/8 29-5/8

26-3/16

11-7/8

14-7/8

11-7/8

14-7/8

17-7/8

30-5/8 10-1/4 23-3/4 24-1/2

30-5/8 10-1/4 29-3/4 30-1/2

30-5/8 10-1/4 35-3/4 36-1/2

23-5/8 24-3/8 23-5/8

29-5/8 30-3/8 29-5/8

35-5/8 36-3/8 35-5/8

17-1/8

Medium

Large

25-5/16 39-3/4 10-1/4 29-3/4 30-1/2 50-9/16 29-5/8 30-3/8 29-5/8 21-11/16 14-7/8

25-5/16 39-3/4 10-1/4 35-3/4 36-1/2 50-9/16 35-5/8 36-3/8 35-5/8 21-11/16 17-7/8

42-1/16

7 ⁷/ ″

″

/ ″ (3.45) DIA

(200.0)

(4.6)

2 REQ'D

5 ³

(128.0)

″

/ ″

(12.7)

(6.4)

5 ³

″

(128.0)

″

/ ″

(5.4)

TYP

7 ²⁹

″ (200.8)

7 ⁷/ ″

(199.9)

(12.7)

TYP

BAFFLE - LEFT

″ (10.0)

1 ²¹

″ (42.1)

MAT'L: 20 GA STEEL

BAFFLE - RIGHT

MAT'L: 20 GA STEEL

2 ¹/ ″

(63.5)

/ ″ (5.56) DIA

2 REQ'D

2 ¹/ ″

(63.5)

/ ″ x / ″ (5.56 x 9.53) SLOT

6 REQ'D

/ ″ (5.56) DIA

4 REQ'D

1 ²¹

″ (42.1)

″ (10.0)

/ ″ x / ″ (5.56 x 9.53) SLOT

⁄

6 REQ'D

4 ⁹

″ (105.2)

″

LEFT

SIDE

RIGHT

SIDE

45°

TYP

(9.2)

2 ⁵

(52.6)

″

SCREW

14 REQ'D

/ ″ (5.56) DIA

4 ⁵⁷

⁄

″

2 REQ'D

(124.2) TYP

SUPPORT

3 REQ'D

OUTDOOR

UNIT

/ ″ (12.7)

8 ⁵

″ (205.3)

TYP

/ ″

″ (9.2)

(6.4)

SUPPORT

MAT'L: 18 GA STEEL

BAFFLE ASSEMBLY

/ ″ (3.45) DIA.

J H

4 REQ'D

A95446

Fig. 2—Wind Baffle Construction for Cube Units

—5—

TABLE 3—WIND BAFFLE DIMENSIONS FOR CUBE UNITS (IN.)

UNIT SIZE

Small

UNIT HEIGHT

21-15/16

23-15/16

25-15/16

27-15/16

29-15/16

31-15/16

33-15/16

21-15/16

23-15/16

25-15/16

27-15/16

29-15/16

31-15/16

33-15/16

35-15/16

37-15/16

25-15/16

27-15/16

29-15/16

31-15/16

33-15/16

35-15/16

37-15/16

39-15/16

19-7/8

21-7/8

23-7/8

25-7/8

27-7/8

29-7/8

31-7/8

19-7/8

21-7/8

23-7/8

25-7/8

27-7/8

29-7/8

31-7/8

33-7/8

35-7/8

23-7/8

25-7/8

27-7/8

29-7/8

31-7/8

33-7/8

35-7/8

37-7/8

13-3/4

18-5/16

25-3/4

28-1/8

32-5/8

40-1/8

10-11/16

20-1/4

24-3/4

32-1/4

11-11/16

16-3/16

23-11/16

3-13/16

8-1/4

19-13/16

21-13/16

23-13/16

25-13/16

27-13/16

29-13/16

31-13/16

19-13/16

21-13/16

23-13/16

25-13/16

27-13/16

29-13/16

31-13/16

33-13/16

35-13/16

23-13/16

25-13/16

27-13/16

29-13/16

31-13/16

33-13/16

35-13/16

37-13/16

17-13/16

19-13/16

21-13/16

23-13/16

25-13/16

27-13/16

29-13/16

17-13/16

19-13/16

21-13/16

23-13/16

25-13/16

27-13/16

29-13/16

31-13/16

33-13/16

21-13/16

23-13/16

25-13/16

27-13/16

29-13/16

31-13/16

33-13/16

35-13/16

8-1/4

Medium

22-1/2

8-1/4

15-13/16

Large

TABLE 4—ESTIMATED PERCENTAGE OF NOMINAL COOLING-CAPACITY LOSSES*

UNIT

NOMINAL

LONG-LINE

EQUIVALENT LINE LENGTH (FT)

VAPOR-LINE

SIZE

(BTUH)

DIAMETER

100

125

150

175

(IN.)†

5/8

18,000

24,000

30,000

36,000

3/4

5/8

3/4

5/8

3/4

N/R

7/8

3/4

42,000

7/8

1-1/8

3/4

N/R

48,000

60,000

7/8

1-1/8

7/8

1-1/8

*The estimated percentage of cooling capacity that must be subtracted from the Detailed Cooling Capacities data specified in outdoor unit-presale literature for any given

indoor/outdoor combination.

†Vapor-line diameter that may be selected for a long-line application. If smaller vapor lines are selected but not specified within the table, large capacity losses will occur

and defrost capabilities will be reduced. If larger vapor lines are selected but not specified within the table, refrigerant oil return will be impaired due to velocity losses.

N/R—Not recommended due to excessive loss of capacity.

For reference only, the close cell insulation material specified for

accessory tubing kits is a compound of vinyl, neoprene, or nitrile

blends of these polymers. Performance requirements include

thermal range of 0° F to 200°F (-17.8° C to 93° C) and a maximum

thermal conductivity of 0.28.

lines and installed system design (indoor coil above or below

outdoor unit.) The piston or TXV provides such flexibility.

The piston should be changed for both indoor coil and outdoor heat

pump unit, depending on system configuration and line length.

Tables 6 and 7 provide necessary changes for a given application.

NOTE: Special consideration must be given to isolating intercon-

necting tubing from building structure. Isolate tubing so that

vibration or noise is not transmitted into structure.

Use Tables 6 and 7 when selecting correct piston size. Outdoor-

unit presale literature must be consulted to determine metering

devices specified for standard applications. After determining

standard application piston size(s), refer to Tables 6 and 7 as they

relate to system design (outdoor unit above or below indoor unit)

per equivalent length of tubing.

III. METERING DEVICE SIZING

The metering device for a long-line application must be flexible

enough to compensate for frictional losses due to long refrigerant

—6—

EXAMPLE:

An 042 size heat pump is 75 ft above an 042 size fan coil.

The 042 size heat-pump presale literature specifies a size

80 indoor piston and size 63 outdoor piston.

To establish correct indoor piston size for a 75 ft vertical

separation, refer to Table 6. For a 75 ft equivalent line

length, the piston change is -5. Therefore subtract 5 from

the original indoor piston size of 80:

80 – 5 = 75

Table 8 provides common piston sizes. In this instance, 75

is not listed, therefore round DOWN to next piston size,

which would be 74.

90° STD

To establish correct outdoor piston size for a 75 ft vertical

separation, refer to Table 7. For a 75 ft equivalent line

length, the piston change is +4. Therefore add 4 to the

original outdoor piston size of 63:

63 + 4 = 67

Since 67 is listed in Table 8, that is the piston which should

be used. If a 67 size piston were not listed, it would be

necessary to round UP to next piston size.

TXVs may be used instead of pistons for indoor-metering devices.

Some fan coils are equipped with a hard-shutoff, bi-flow TXV

standard, and no change is required. When sizing an accessory

TXV for long-line applications, TXV should be the same nominal

tonnage as outdoor unit. Refer to presale literature for kit part

numbers.

90° LONG RAD

TABLE 6—CALCULATION OF INDOOR PISTON NO.

OUTDOOR UNIT ABOVE INDOOR

PISTON CHANGE

0-25

-3

26-50

51-75

-5

76-100

101-125

126-150

-7

-9

-10

OUTDOOR UNIT BELOW INDOOR

PISTON CHANGE

0-25

26-50

A92498

45° STD

Fig. 3—Tube Bend Losses

TABLE 7—CALCULATION OF OUTDOOR PISTON NO.

TABLE 5—FITTING LOSSES IN EQUIVALENT FT

OUTDOOR UNIT ABOVE INDOOR

REFERENCE DIAGRAM IN FIG. 1

TUBE SIZE OD

(IN.)

PISTON CHANGE

0-50

5/8

3/4

1.6

1.8

2.0

2.6

1.0

1.2

1.4

1.7

0.8

0.9

1.0

1.3

51-75

+10

76-100

101-125

126-150

7/8

1-1/8

OUTDOOR UNIT BELOW INDOOR

PISTON CHANGE

0-50

NOTE: If total equivalent horizontal length is 100 ft or longer,

both indoor and outdoor pistons must be increased 1 full piston

size, in addition to changes required by Tables 6 and 7.

IV. LIQUID-LINE SOLENOID AND TUBING CONFIGU-

RATION

After finding appropriate change in piston size, add or subtract the

change from original piston number. If piston size is decreased,

round new piston number down to nearest common piston number

found in Table 8. If piston size is increased, round new piston

number up to nearest common piston number found in Table 8.

There are 2 types of liquid-line solenoids: 1 for single-flow

applications and the other for bi-flow applications. The purpose of

having 2 solenoids is to minimize the valve internal-pressure drop

in accordance with refrigerant flow direction and liquid migration

to the compressor. The bi-flow solenoid is designed to have

minimal refrigerant-pressure drop in either flow direction, which

makes it suitable for heat pump usage. Refer to Table 9 for

liquid-line solenoid kit part numbers.

—7—

TABLE 8—COMMON PISTON SIZES

EXAMPLE:

To calculate additional charge required for a 25–ft line set:

25 ft – 15 ft = 10 ft X 0.6 oz/ft = 6 oz of additional charge

CHECK-FLO-

RATER™

CHECK-FLO-

RATER™

CHATLEFF

—

101

104

—

The rating-plate charge of a given outdoor unit is for a standard

application of 15 ft of interconnecting tubing. The rating-plate

charge can be found on outdoor unit-rating plate or in outdoor

unit-presale literature. Long-line applications do not require addi-

tional oil charge.

—

VI. 2–SPEED APPLICATIONS

—

Outdoor units may be connected to indoor section using accessory

tubing package or field-supplied refrigerant grade tubing of correct

size and condition. In long–line applications, 2–speed units are

handled basically the same way as the single-speed units. There are

2 major differences:

—

1. For tubing up to 100 ft:

Liquid tube diameters and refrigerant connection diameters

for all sizes are 3/8 in.

Vapor tube diameter for the 036 and 048 is 7/8 in.; 060 is

1–1/8 in.

Vapor refrigerant connection diameter for all sizes is 7/8 in.

DO NOT INSTALL EQUIVALENT INTERCONNECT-

ING TUBING LENGTHS GREATER THAN 100 FT.

—

101

104

109

2. Do not increase or decrease tubing sizes.

For other applications see the previous sections under Long-Line

Guidelines.

UNIT IDENTIFICATION

I. PRODUCT NUMBER STAMPED ON UNIT-RATING

PLATE

NOTE: When installing a liquid-line solenoid, the system may

require a minimum 60va low-voltage transformer.

The unit product number has 16 positions containing groups of

numbers and letters that indicate specific information about the

unit. Listed below is the breakdown of the 16 positions.

Positions 1, 2, and 3—Product Series

Example:

A 500–series number indicates a split-system condensing unit and

a 600–series number indicates a split-system heat pump.

Position 4—Model Letters

Each type of solenoid has an indicator flow arrow stamped on the

valve body. When solenoid is closed (not energized) and pressure

is applied in direction of flow arrow, complete shutoff occurs. If

pressure is applied against direction of flow arrow, leakage

through valve occurs. When determining proper installation of

valve within liquid line, 2 considerations must be made:

1. Direction of flow arrow

New models are introduced with the letter A, and subsequent

model changes are identified by changing to the next letter, as B,

then C, and so forth.

Position 5—Electrical Characteristics

Example:

2. Where solenoid is installed in system.

TXVs can only be substituted for liquid-line solenoids in single-

flow air conditioning systems. Bi-flow TXVs allow liquid migra-

tion to coldest point during off cycles, which could allow liquid

into compressor.

J—208–230, 1 Phase, 60 Hertz

Fig. 4 through 7 detail proper installation of liquid-line solenoid

and provide applications where TXVs may be substituted. Refer-

ence all notes of the appropriate figures.

N—208/230, 208/240, 1 Phase, 60 Hertz

P—208/230, 208/240, 3 Phase, 60 Hertz

E—460, 3 Phase, 60 Hertz

Q—220, 3 Phase, 50 Hertz

S—220/240, 1 Phase, 50 Hertz

TABLE 9—LIQUID-LINE SOLENOID KIT PART NUMBERS

Z—380/415, 3 Phase, 50 Hertz

Position 6—Fuel and Controls

Not applicable on condensing units or heat pumps, so the letter ’X’

is used to signify ’none.’

TYPE OF VALVE

Single Flow

Bi-Flow

PART NO.

KAALS0101LLS

KHALS0401LLS

Positions 7, 8, and 9—Nominal Cooling Capacity (in thousands

Btuh)

V. CHARGING INFORMATION

Weigh in appropriate refrigerant charge, then use the standard

practices of superheat-charging method for piston applications and

subcooling-charging method for TXV applications to confirm

correct charge. The standard charging methods can be found on

outdoor unit-information plate, in unit Installation Instructions, or

in the Service Manual. Since total system charge is increased for

long-line applications, it may be necessary to calculate the

additional refrigerant charge. Since long-line applications only

involve 3/8-in. liquid lines, the additional refrigerant charge

required is 0.6 oz of Refrigerant 22 (R-22) per ft of 3/8-in. liquid

line over 15 ft.

Example: 036 = 36,000 Btuh or 3–ton capacity.

Positions 10, 11, and 12—Not applicable on condensing units or

heat pumps, so the number ’zero’ is used to signify ’none.’

Position 13—Brand Name

Example:

A—Common unit —U.S.A. Only

Position 14—Unit Series

New units are introduced with the letter A, and subsequent major

component variations, such as in compressor, fan motor, coil

circuitor size, etc., are identified by changing to the next letter, as

B, then C, and so forth.

—8—

Positions 15 and 16—Product Variations

Example:

AA—Standard unit

52—Last week of a year

Positions 3 and 4—Year of Manufacture

Example:

Other letters—For product variations from standard

94—1994

Position 5—Manufacturing Site

Example:

A–Indianapolis

E–Collierville

Positions 6 through 10—Serial Number

II. SERIAL NUMBER IDENTIFICATION

The unit serial number has 10 positions containing groups of

numbers and a letter that indicate specific information about the

unit. Listed below is the breakdown of the 10 positions.

Positions 1 and 2—Week of Manufacture

Example:

01—First week of a year

175' MAX.

GROUND LEVEL

BASEMENT

A90074

Fig. 4—Application with Air Conditioner Installed in a Horizontal Configuration

175' MAX.

GROUND LEVEL

BASEMENT

A90075

Fig. 5—Application with Heat Pump Installed in a Horizontal Configuration

—9—

TRAP

50' MAX.

HEAT PUMP ONLY

GROUND LEVEL

A90076

Fig. 6—Application with Air Conditioner or Heat Pump Installed with Indoor Unit Above Outdoor Unit

CABINET

III. INFORMATION PLATE—RELIANT PRODUCTS

Certain maintenance routines and repairs require removal of

cabinet panels. There are 4 basic cabinet designs for air condition-

ers and heat pumps. (See Fig. 8.) The horizontal discharge unit will

be discussed in a separate section of this manual. Note that

separate sections apply according to date of manufacture.

The information plate is secured to the front of the control box and

provides a cover for it. (See Fig. 9.) This plate also provides a

surface to attach the wiring schematic, superheat-charging tables

with instructions, and warning labels. The plate has 2 tabs on the

top edge that are bent down at slightly more than 90°. When the

information plate is removed, these tabs can be inserted into 2

mating slots in the bottom-front edge of the control box, and the

plate will hang down, forming a lower front panel. (See Fig. 10.)

This is convenient where access to the controls is required while

the unit is operating. The information plate on the small size casing

completely covers the opening below the control box. On larger

models, the information plate may not cover the entire opening. In

this instance, the top cover can be removed and placed on its side

to cover the additional space.

I. REMOVE TOP COVER—BEFORE 1/1/92

NOTE: This section applies to all Reliant products made prior to

January 1, 1992.

1. Turn off all power to outdoor and indoor units.

2. Remove screws holding top cover to coil grille and corner

posts.

3. Remove access panel.

IV. CONTROL-BOX COVER—CUBE PRODUCTS

4. Remove information plate.

This panel contains much of the same information as the informa-

tion plate mentioned previously, but is designed only to cover the

control box.

5. Disconnect fan motor wires, cut wire ties, and remove wire

ties from control box. Refer to unit-wiring label.

6. Lift top cover from unit.

V. REMOVE TOP COVER— AFTER 1/1/92

7. Reverse sequence for reassembly.

NOTE: The section applies to all Reliant Products made after

II. REMOVE FAN-MOTOR ASSEMBLY—BEFORE 1/1/92

January 1, 1992.

NOTE: This section applies to all Reliant products made prior to

1. Turn off all power to outdoor and indoor units.

January 1, 1992.

2. Remove 5 screws holding top cover to coil grille and coil

tube sheet.

1. Perform items 1 through 6 above.

3. Remove 2 screws holding control-box cover.

4. Remove 2 screws holding information plate.

2. Remove nuts holding fan-motor top cover.

3. Remove motor and fan blade assembly.

4. Reverse sequence for reassembly.

5. Disconnect fan motor wires, cut any wire ties, and move

wires out of control box and through tube clamp on back of

control box.

5. Prior to applying power, check that fan rotates freely.

—10—

HEAT PUMP ONLY

150' MAX.

A90077

Fig. 7—Application with Air Conditioner or Heat Pump Installed Above Indoor Unit

6. Lift top cover from unit.

7. Reverse sequence for reassembly.

VI. REMOVE FAN-MOTOR ASSEMBLY—AFTER 1/1/92

NOTE: This section applies to all Reliant products made after

January 1, 1992

1. Perform items 1, 3, 4, and 5 above. (Note item 2 is not

required.)

2. Remove 4 screws holding wire basket to top cover.

3. Lift wire basket from unit.

4. Remove nuts holding fan motor to wire basket.

5. Remove motor and fan blade assembly.

6. Pull wires through wire raceway to change motor.

7. Reverse sequence for reassembly.

8. Prior to applying power, check that fan rotates freely.

—11—

A94003

Fig. 8—Basic Cabinet Designs

ELECTRICAL

I. ALUMINUM WIRE

CAUTION: Aluminum wire may be used in the branch

WARNING: Exercise extreme caution when working on

any electrical components. Shut off all power to system

prior to troubleshooting. Some troubleshooting tech-

niques require power to remain on. In these instances,

exercise extreme caution to avoid danger of electrical

shock. ONLY TRAINED SERVICE PERSONNEL

SHOULD PERFORM ELECTRICAL TROUBLE-

SHOOTING.

circuit (such as the circuit between the main and unit

disconnect), but only copper wire may be used between

the unit disconnect and the unit on Bryant systems.

Whenever aluminum wire is used in the branch-circuit wiring with

this unit, adhere to the following recommendations.

Connections must be made in accordance with the National

Electrical Code (NEC), using connectors approved for aluminum

wire. The connectors must be UL-approved (marked Al/Cu with

the UL symbol) for the application and wire size. The wire size

selected must have a current capacity not less than that of the

copper wire specified and must not create a voltage drop between

the service panel and the unit in excess of 2 percent of the

unit-rated voltage.

Troubleshooting charts for air conditioning and heat pump units

are provided in the back of this manual. They enable the service

technician to use a systematic approach to locate the cause of a

problem and correct system malfunctions.

To prepare the wire before installing the connector, all aluminum

wire must be ″brush scratched″ and coated with a corrosion

inhibiter such as Pentrox A. When it is suspected that the

—12—

II. CONTACTORS

NOTE: The section applies to single-speed models only.

The contactor provides a means of applying power to unit using

low voltage (24v) from transformer in order to power the contactor

coil. (See Fig. 11.) Depending on unit model, you may encounter

single-, double-, or triple-pole contactors to break power. One side

of the line may be electrically energized, so exercise extreme

caution when troubleshooting.

SEFL JOSDJ

SEFL JOSDJ PAASFLDLKREW

SEFL JOSDJ ATC

SEFL JOSDJ UTUHD

SEFL JOSDJC MD

SEFL JOSDJHR ITYALK

SEFL JOSDJ

The contactor coil for residential air-conditioning units and heat

pumps is powered by 24vac. If contactor does not operate:

1. With power off, check whether contacts are free to move.

Check for severe burning or arcing on contact points.

2. With power off, use ohmmeter to check for continuity of

coil. Disconnect leads before checking. A low-resistance

reading is normal. Do not look for a specific value, as

different part numbers have different resistance values.

3. Reconnect leads and apply low-voltage power to contactor

coil. This may be done by leaving high-voltage power to

outdoor unit off, and turning thermostat to heat or cool.

Check voltage at coil with voltmeter. Reading should be

between 20v and 30v. Contactor should pull in if voltage is

correct and coil is good. If contactor does not pull in,

change contactor.

A88411

Fig. 9—Information Plate

connection will be exposed to moisture, it is very important to

cover the entire connection completely to prevent an electrochemi-

cal action that will cause the connection to fail very quickly. Do

not reduce the effective size of wire, such as cutting off strands so

that the wire will fit a connector. Proper size connectors should be

used. Check all factory and field electrical connections for

tightness. This should also be done after the unit has reached

operating temperatures, especially if aluminum conductors are

used.

4. With high-voltage power off and contacts pulled in, check

for continuity across contacts with ohmmeter. A very low or

zero resistance should be read. Higher readings could

indicate burned or pitted contacts which may cause future

failures.

SEFL JOSDJ

SEFL JOSDJ PAASFLDLKREW

SEFL JOSDJ ATC

SEFL JOSDJ UTUHD

SEFL JOSDJC MD

SEFL JOSDJHR ITYALK

SEFL JOSDJ

SEFL JOSDJ PAASFLDLKREW

SEFL JOSDJ ATC

SEFL JOSDJ UTUHD

SEFL JOSDJC MD

SEFL JOSDJ

SEFL JOSDJHR ITYALK

SEFL JOSDJ

A88412

A88413

Fig. 10—Information Plate Removed/Installed Below Control Box

—13—

A91455

Fig. 12—Capacitors

A88350

Use the following formula to calculate capacitance:

Capacitance (mfd) = (2650 X amps) divided by (volts)

Fig. 11—Contactor

III. CAPACITORS

3. Remove any capacitor that shows signs of bulging, dents, or

leaking. Do not apply power to a defective capacitor as it

may explode.

CAUTION: Capacitors can store electrical energy when

power is off. Electrical shock can result if you touch the

capacitor terminals and discharge the stored energy.

Exercise extreme caution when working near capacitors.

With power off, discharge stored energy by shorting

across the capacitor terminals with a 15,000-ohm, 2-watt

resistor.

START CAPACITORS AND PTC DEVICES

Sometimes under adverse conditions, a standard run capacitor in a

system is inadequate to start compressor. In these instances, a

start-assist device is used to provide an extra starting boost to

compressor motor. The first device is called a positive-temperature

coefficient (PTC) or thermistor. (See Fig. 13.) It is a resistor wired

in parallel with the run capacitor. As current flows through the

PTC at start-up, it heats up. As it heats up, its resistance increases

greatly until it effectively lowers the current through it to an

extremely low value. This, in effect, removes it from the circuit.

NOTE: If bleed resistor is wired across start capacitor, it must be

disconnected to avoid erroneous readings when ohmmeter is

applied across capacitor. (See Fig. 12.)

CAUTION: Always check capacitors with power off.

Attempting to troubleshoot a capacitor with power on can

be dangerous. Defective capacitors may explode when

power is applied. Insulating fluid inside is combustible

and may ignite, causing burns.

12.5-22.5

OHMS

12.5 OHM

(BEIGE COLOR)

Capacitors are used as a phase-shifting device to aid in starting

certain single-phase motors. Check capacitors as follows.

25-45

OHMS

20-36

OHMS

1. After power is off, discharge capacitors as outlined above.

Disconnect capacitor from circuit. Put ohmmeter on R X

10k scale. Using ohmmeter, check each terminal to ground

(use capacitor case). Discard any capacitor which measures

1/2–scale deflection or less. Place ohmmeter leads across

capacitor and place on R X 10k scale. Meter should jump to

a low-resistance value and slowly climb to higher value.

Failure of meter to do this indicates an open capacitor. If

resistance stays at zero or a low value, capacitor is inter-

nally shorted.

BLUE

20 OHM

(BLUE COLOR)

25 OHM

(BLUE COLOR)

A88414

Fig. 13—PTC Devices

After system shutdown, resistor cools and resistance value returns

to normal until next time system starts. If indoor coil does not have

a bleed-type expansion device, it may be necessary to remove start

thermistor and replace with accessory start capacitor and relay.

Consult pre-sale literature for application of start kits. Thermistor

device is adequate for most conditions; however, in systems where

off-cycle is short, device cannot cool fully and becomes less

effective as a start device. It is an easy device to troubleshoot.

2. Capacitance testers are available which read value of

capacitor. If value is not within ± 10 percent value stated on

capacitor, it should be changed. If capacitor is not open or

shorted, the capacitance value is calculated by measuring

voltage across capacitor and current it draws.

WARNING: Exercise extreme caution when taking

readings while power is on. Electrical shock can cause

personal injury or death.

1. Shut off all power to system.

2. Check thermistor with ohmmeter as described below.

3. Shut off all power to unit.

—14—

4. Remove PTC from unit. Wait at least 10 minutes for PTC to

cool to ambient temperature.

CAUTION: Do not check winding at compressor termi-

nals with pressure in the system. Check resistance by

removing wires attached at the compressor contactor and

run capacitor.

5. Measure resistance of PTC with ohmmeter as shown in

Fig.13.

The cold resistance (RT) of any PTC device should be approxi-

mately 100 – 180 percent of device ohm rating.

12.5–ohm PTC = 12.5–22.5 ohm resistance — beige color

25–ohm PTC = 25–45 ohm resistance — blue color

20–ohm PTC = 20–36 ohm resistance — blue color

3. Obtain

start capacitor in the range of

150–180µF[@0330] volts rating. Connect 8–gauge wires

with insulated clips or terminals to the H and C terminals of

the run capacitor.

If PTC resistance is appreciably less than rating or more than 200

percent higher than rating, device is defective.

4. Turn power on to unit. If compressor starts, immediately

remove start-capacitor wires from H and C terminals of run

capacitor, using a pair of insulated, needle-nose pliers. DO

NOT leave start capacitor attached to run capacitor for more

than 3 seconds, even if compressor doesn’t start.

If thermistor is good and compressor does not start:

1. Disconnect thermistor from starting circuit.

2. Give compressor a temporary capacitance boost (see next

section).

5. Discharge start capacitor by using a pair of insulated,

needle-nose pliers and shorting a 15,000 ohm, 2 watt

resistor across terminals.

3. Run compressor for 10 minutes, shut off, and allow system

pressure to equalize.

4. Reconnect start thermistor.

NOTE: Some start capacitors already have a bleed resistor

attached. If so, it will discharge itself over a short period of time.

5. Try restarting compressor without boost capacitor. If after 2

attempts compressor does not start, remove thermistor. Add

an accessory start-capacitor relay package.

6. Run compressor 10 minutes. Stop and allow unit to sit idle

for 5 minutes.

TEMPORARY CAPACITANCE BOOST

7. Check system pressure equalization.

WARNING: Do not under any circumstances attach a

temporary boost capacitor directly to the compressor

terminals. Serious personal injury can result. Exercise

extreme caution with this procedure when high-voltage

power is on.

8. Attempt to restart without capacitance boost.

If PTC thermistor device is inadequate as start device, a start

capacitor and relay may be added to system to ensure positive start.

Capacitor is wired in parallel with run capacitor through normally

closed set of contacts on a device called start relay. The relay coil

is wired across start and common terminals of compressor. The

added capacitance gets the compressor started. As compressor

comes up to speed, voltage across start and common terminals

increases to a value high enough to cause start relay to energize.

This opens normally closed contacts and removes start capacitor

from circuit. In actual practice, this occurs in a fraction of a

second.

There are times when a temporary capacitance boost is needed to

get compressor started. (See Fig. 14.) If compressor motor does not

start, it may be due to low-line voltage, improper pressure

equalization, weak run capacitor, or a seized compressor. Check

each possibility and attempt capacitance boost before adding

auxiliary start capacitor and relay.

NOTE: If bleed resistor is wired across start capacitor, it must be

disconnected to avoid erroneous readings when ohmmeter is

applied across capacitor.

220-V FROM UNIT

CONTACTOR

To check start relay and capacitor:

1. Turn off all power to unit.

2. Discharge start and run capacitors as outlined earlier.

COMP. RUN

CAPACITOR

3. Most start capacitors will have a 15,000 ohm, 2 watt bleed

resistor. Disconnect these devices from system.

Start capacitor can be inspected visually. It is designed for short

duration or intermittent duty. If left in circuit for prolonged period,

start capacitor blows through a specially designed bleed hole. If it

appears blown, check for welded contacts in start relay. Start

capacitor can be checked by ohmmeter method discussed earlier.

START (BOOST)

CAPACITOR

Start relay is checked with ohmmeter. Check for continuity across

coil of relay. You should encounter a high resistance. Since relay

contacts are normally closed, you should read low resistance

across them. Both PTC device and capacitor-relay start system are

standard equipment on some of these units. They are also available

as accessories and may be field-installed.

A88349

Fig. 14—Capacitance Boosting

1. Turn off all power to unit. There may be more than one

power source to condensing unit.

NOTE: If a PTC is already installed, remove it from the system

IV. CYCLE PROTECTOR

Solid-state cycle-protector device protects unit compressor by

preventing short cycling. After a system shutdown, cycle protector

provides for a 5 ± 2-minute delay before compressor restarts. On

normal start-up, a 5-minute delay occurs before thermostat closes.

After thermostat closes, cycle protector device provides a 3-sec

delay on HN67PA025, HN67ZA003, and HN67ZA008. (See Fig.

15, 16, and 17.)

by pulling PTC wires from H and C terminals on run capacitor.

2. Check compressor for ground or open windings. If wind-

ing’s resistance is within manufacturer’s recommendations,

proceed. (See Reciprocating Compressor Section II-

Electrical Failures for proper compressor-winding check.)

—15—

HN67ZA002

A91438

HN67ZA008

A94005

T3 BLK

T1 YEL T2 VIO

HN67PA025

HN67ZA003

A91439

A91440

Fig. 15—Cycle-Protector Device

Cycle-protector device is simple to troubleshoot. Only a voltmeter

capable of reading 24v is needed. Device is in control circuit;

therefore, troubleshooting is safe with control power (24v) on and

high-voltage power off.

no circuit through the crankcase heater because both leads are

connected to the same side of the line. This allows the heater to

operate when the system is not calling for heating/cooling. The

heater does not operate when the system is calling for

heating/cooling. On units with 2 or 3 pole contactors, the crank-

case heater is connected to the line side of the contactor and is not

controlled by the contactor contacts.

The crankcase heater is powered by high-voltage power of unit.

Use extreme caution troubleshooting this device with power on.

The easiest method of troubleshooting is to apply voltmeter across

crankcase heater leads to see if heater has power. Do not touch

heater. Carefully feel area around crankcase heater. If warm,

crankcase heater is probably functioning. Do not rely on this

method as absolute evidence heater is functioning. If compressor

has been running, the area will still be warm.

With power off and heater leads disconnected, check across leads

with ohmmeter. Do not look for a specific resistance reading.

Check for resistance or an open circuit. Change heater if an open

circuit is detected. Some crankcase heaters in this series of units

are equipped with a crankcase-heater switch. This energy-saving

device shuts off power to heater when temperatures are high

enough that heater is not needed. Be sure this switch is functioning

normally before condemning crankcase heater.

With high-voltage power off, attach voltmeter leads across T1 and

T3 and set thermostat so that Y terminal is energized. Make sure

all protective devices in series with Y terminal are closed.

Voltmeter should read 24v across T1 and T3. With 24v still

applied, move voltmeter lead from T1 terminal to T2 terminal

across T2 and T3. After 5 ± 2 minutes, voltmeter should read 24v,

indicating control is functioning normally. If no time delay is

encountered or device never times out, change control.

V. CRANKCASE HEATER

Crankcase heater is a device for keeping compressor oil warm. By

keeping oil warm, refrigerant does not migrate to and condense in

compressor shell when the compressor is off. This prevents

flooded starts which can damage compressor.

Crankcase heaters come in 2 basic types: wraparound-(bellyband)

type that is wrapped externally around compressor shell, and

insertion-type that is inserted into compressor oil well in shell of

compressor. Both types are used in outdoor units.

On units that have a single-pole contactor, the crankcase heater is

wired parallel with the contactor contacts and in series with the

compressor. (See Fig. 18.) When the contacts are open, a circuit is

completed from the line side of the contactor, through the

crankcase heater, through the run windings of the compressor, and

to the other side of the line. When the contacts are closed, there is

VI. TIME-DELAY RELAY

The time-delay relay (TDR) is a solid-state-controlled, recycle-

delay timer which keeps the indoor blower operating for 90 sec

after thermostat is satisfied. This delay enables the blower to

remove residual cooling in the coil after compression shutdown,

—16—

OPERATING

TIME

OPERATING

TIME

SEC

5 MIN

BLK DENOTES CLOSED CONTACTS

HN67ZA002

BLK DENOTES CLOSED CONTACTS

HN67PA025, HN67ZA003, HN67ZA008

A91436

A91437

Fig. 16—Cycle-Protector Sequence

CUT YELLOW WIRE

BETWEEN CONTACTOR AND

LOW-PRESSURE SWITCH

SAFETY

CONTROL

YEL

BRN

YEL

TERMINAL

BOARD

CONNECTION

TERMINAL

BOARD

CONNECTION

VIO

LOGIC

BLK

A88415

Fig. 17—Cycle-Protector Wiring

TDR is reset, and the fan relay remains energized. The TDR is a

24v device that operates within a range of 15 to 30v and draws

about 0.5 amps.

DSV

If the blower runs continuously instead of cycling off when the fan

switch is set on AUTO, the TDR is probably defective and must be

replaced.

VII. PRESSURE SWITCHES

Pressure switches are protective devices wired into control circuit

(low voltage). They shut off compressor if abnormally high or low

pressures are present in the refrigeration circuit. Depending on unit

model, you may find a low- and/or high-pressure switch in system.

LOW-PRESSURE SWITCH

Located on suction line of condensing unit only, the low-pressure

switch protects against low-suction pressures caused by such

events as loss of charge, low airflow across indoor coil, dirty

filters, etc. It opens on a pressure drop at about 27 psi. If system

pressure is above this, switch should be closed. To check switch,

turn off all power to unit, disconnect leads on switch, and apply

ohmmeter leads across switch. You should have continuity on a

good switch. Because these switches are attached to refrigeration

system under pressure, it is not advisable to remove this device for

troubleshooting unless you are reasonably certain that a problem

exists. If switch must be removed, remove and recover all system

charge so that pressure gages read 0 psi.

A91426

Fig. 18—Wiring for Single-Pole Contactor

thereby improving the efficiency of the system. The sequence of

operation is that on closure of the wall thermostat and at the end of

a fixed on-delay of 1 sec, the fan relay is energized. When the

thermostat is satisfied, an off-delay is initiated. When the fixed

delay of 90 ± 20 sec is completed, the fan relay is de-energized and

fan motor stops. If the wall thermostat closes during this delay, the

—17—

2. Remove control-box cover for access to electrical compo-

nents and defrost-control board.

CAUTION: Wear safety glasses and gloves when work-

ing with refrigerants.

3. Disconnect defrost-thermostat leads from control board and

connect to ohmmeter. Thermostat leads are the black,

insulated wires connected to DFT and R terminals on

control board. Resistance reading may be zero (indicating

closed defrost thermostat) or infinity (∞ for open thermo-

stat) depending on outdoor temperature.

Apply heat with torch to solder joint and remove switch. Wear

safety glasses when using torch. Have quenching cloth available.

Oil vapor in line may ignite when switch is removed. Braze in

1/4-in. flare fitting and screw on replacement pressure switch.

HIGH-PRESSURE SWITCH

4. Jumper between DFT and R terminals on control board as

shown in Fig. 19.

Located on discharge line, the high-pressure switch protects

against high-discharge pressures caused by such events as over-

charge, condenser-fan motor failure, system restriction, etc. It

opens on pressure rise at about 435 psi. If system pressures go

above this setting during abnormal conditions, the switch opens.

Do not attempt to simulate these system abnormalities as high

pressures pose a serious safety hazard. High-pressure switch is also

checked with an ohmmeter similar to checking low-pressure

switch. If system pressure is below 435 psi, the switch shows

continuity. It is replaced in the same manner as low-pressure

switch. Observe all safety precautions.

5. Disconnect outdoor fan motor lead from OF2. Tape lead to

prevent grounding.

6. Turn on power to outdoor unit.

7. Restart unit in heating, allowing frost to accumulate on

outdoor coil.

8. After a few minutes in heating, liquid-line temperature at

defrost thermostat should drop below closing set point of

defrost thermostat of approximately 30°F. Using ohmmeter,

check resistance across defrost-thermostat leads. Resistance

of zero indicates defrost thermostat is closed and operating

properly.

LIQUID-LINE PRESSURE SWITCH

Located on liquid line of heat pump only, the liquid-line pressure

switch functions similar to conventional low-pressure switch.

Because heat pumps experience very low suction pressures during

normal system operation, a conventional low-pressure switch

cannot be installed on suction line. This switch is installed in liquid

line instead and acts as loss-of-charge protector. The liquid line is

the low side of the system in heating mode. It operates identically

to low-pressure switch except it opens at 7 psi when the heating

piston is in the liquid valve or 27 psi when the heating piston is in

the liquid line. Troubleshooting and removing this switch is

identical to procedures used on other switches. Observe same

safety precautions.

9. Remove protective cover from TP1 and TP2 speed-up

terminals. Install jumper wire on speed-up terminals. This

reduces the timing sequence to 1/60 of original time. (See

Fig. 20.) Since Fig. 20 shows timing cycle set at 30 minutes,

unit initiates defrost within approximately 30 sec; if setting

is at 50 minutes, within 50 sec; 90 minutes, within 90 sec.

When you hear the reversing valve change position, remove

protective cover/jumper. Otherwise, control will terminate

normal 10-minute defrost cycle in approximately 10 sec.

CAUTION: Exercise extreme caution when shorting

speed-up pins. If pins are accidentally grounded, damage

to the control board will occur.

VIII. DEFROST THERMOSTATS

Defrost thermostat signals heat pump that conditions are right for

defrost or that conditions have changed to terminate defrost. It is

a thermally actuated switch clamped to outdoor coil to sense its

temperature. Normal temperature range is closed at 30° ± 3°F and

open at 80° ± 5°F.

10. Unit is now operating in defrost mode. Using voltmeter,

check between C and W2 as shown in Fig. 21. Reading on

voltmeter should indicate 24v. This step ensures defrost

relay contacts have closed, energizing supplemental heat

(W2) and reversing valve solenoid (O).

NOTE: The defrost thermostat must be located on the liquid side

of the outdoor coil on the bottom circuit and as close to the coil as

possible.

IX. DEFROST-CONTROL BOARD

11. Unit should remain in defrost no longer than 10 minutes.

Actual time in defrost depends on how quickly speed-up

jumper is removed. If it takes 3 sec to remove speed-up

jumper after unit has switched to defrost, only 7 minutes of

defrost cycle remains.

Solid-state defrost boards used on heat pumps replace electrome-

chanical timer and defrost relay found on older defrost systems.

The defrost-control board can be field-set to check need for defrost

every 30, 50, or 90 minutes of operating time by connecting the

jumper (labeled W1 on the circuit board) to the terminal for the

defrost time desired. The board is set at factory for 90 minutes. The

defrost period is field-selectable, depending upon geographic areas

and defrost demands. Two types of defrost boards are used, and

functions are described in the sections to follow.

12. After a few minutes in defrost (cooling) operation, liquid

line should be warm enough to have caused defrost-

thermostat contacts to open. Check resistance across defrost

thermostat. Ohmmeter should read infinite resistance, indi-

cating defrost thermostat has opened at approximately 80°F.

Troubleshooting defrost control involves a series of simple steps

that indicate whether or not board is defective.

13. Shut off unit power and reconnect fan lead.

NOTE: This procedure allows the service technician to check

control board and defrost thermostat for defects. First troubleshoot

to make sure unit operates properly in heating and cooling modes.

This ensures operational problems are not attributed to the defrost-

control board.

14. Remove jumper wire from speed-up terminal and reinsert

cover on speed-up terminals. Failure to remove jumper

causes unit to speed up operating cycles continuously.

15. Remove jumper between DFT and R terminals. Reconnect

defrost thermostat leads.

HK32FA003, 006 DEFROST CONTROL

16. Replace control-box cover. Restore power to unit.

This control board utilizes screw terminals for the low-voltage

field wiring. The board has a feature that allows the heat pump to

restart in defrost if room thermostat is satisfied during defrost. To

troubleshoot the board, perform the following items.

If defrost thermostat does not check out following above items or

incorrect calibration is suspected, check for a defective thermostat

as follows.

1. Turn thermostat to OFF. Shut off all power to outdoor unit.

1. Follow items 1-5 above.

—18—

OF1

OF2

OF1

TI DFT

TEST 30 50 90

DFT

CES0110063,

CES0130024

A91442

HK32FA003/HK32FA006

A88402

Fig. 19—Jumper DFT and R Terminals

2. Using thermocouple temperature-measuring device, route

sensor or probe underneath coil (or other convenient loca-

tion). Attach to liquid line near defrost thermostat. Insulate

for more accurate reading.

4. Jumper between DFT and R terminals on control board as

shown in Fig. 21.

5. Disconnect outdoor fan-motor lead from OF2. Tape lead to

prevent grounding.

6. Turn on power to outdoor unit.

7. Restart unit in heating mode, allowing frost to accumulate

on outdoor coil.

3. Turn on power to outdoor unit.

4. Restart unit in heating mode.

5. Within a few minutes, liquid-line temperature drops within

a range causing defrost thermostat contacts to close. Tem-

perature range is from 33°F to 27°F. Notice temperature at

which ohmmeter reading goes from ∞ to zero ohms.

Thermostat contacts close at this point.

8. After a few minutes in heating mode, liquid-line tempera-

ture at defrost thermostat should drop below closing set

point of defrost thermostat of approximately 30°F. Check

resistance across defrost thermostat leads using ohmmeter.

Resistance of zero indicates defrost thermostat is closed and

operating properly.

9. Short between the speed-up terminals using a thermostat

screwdriver. This reduces the timing sequence to 1/256 of

original time. (See Fig. 20 and Table 10.)

6. Remove protective cover from TP1 and TP2 speed-up

terminals, and install jumper wire on the speed-up termi-

nals.

7. Unit changes over to defrost within 90 sec (depending on

timing cycle setting). Liquid-line temperature rises to range

where defrost thermostat contacts open. Temperature range

is from 75°F to 85°F. Resistance goes from zero to ∞ when

contacts open.

NOTE: Fig. 20 shows timing cycle set at 30 minutes; however,

for the CES30110063 board the timing cycle will be set for 90 min

and unit initiates defrost within approximately 21 sec. When you

hear the reversing valve change position, remove screwdriver

immediately. Otherwise, control will terminate normal 10-minute

defrost cycle in approximately 2 sec.

8. If either opening or closing temperature does not fall within

above ranges or thermostat sticks in 1 position, replace

thermostat to ensure proper defrost operation.

CAUTION: Exercise extreme caution when shorting

speed-up pins. If pins are accidentally shorted to other

terminals, damage to the control board will occur.

CES0110063 DEFROST CONTROL

Some heat pumps built in 1991 and later incorporate a new defrost

control. The screw terminals found on the previous control board

have been replaced by a connector plug with stripped-wire leads.

This control board also contains the feature that allows the heat

pump to restart in defrost if the room thermostat is satisfied during

defrost. The board also contains a 5-minute cycle protector that

prevents the unit from short cycling after it cycles off or after a

power interruption. To troubleshoot the board, perform the follow-

ing items.

10. Unit is now operating in defrost mode. Check between C

and W2 using voltmeter as shown in Fig. 21. Reading on

voltmeter should indicate 24v. This step ensures defrost-

relay contacts have closed, energizing supplemental heat

(W2) and reversing valve solenoid (O).

11. Unit should remain in defrost no longer than 10 minutes.

Actual time in defrost depends on how quickly speed-up

jumper is removed. If it takes 2 sec. to remove speed-up

jumper after unit has switched to defrost, the unit will

switch back to heat mode.

12. After a few minutes in defrost (cooling) operation, liquid

line should be warm enough to have caused defrost-

thermostat contacts to open. Check resistance across defrost

thermostat. Ohmmeter should read infinite resistance, indi-

cating defrost thermostat has opened at approximately 80°F.

1. Turn thermostat to OFF. Shut off all power to outdoor unit.

2. Remove control-box cover for access to electrical compo-

nents and defrost-control board.

3. Disconnect defrost-thermostat leads from control board,

and connect to ohmmeter. Thermostat leads are the black,

insulated wires connected to DFT and R terminals on

control board. Resistance reading may be zero (indicating

closed-defrost thermostat), or infinity (∞ for open thermo-

stat) depending on outdoor temperature.

—19—

OF1 OF2

OF2

OF1

TI DFT

TEST 30 50 90

DFT

50 90

HK32FA003/HK32FA006

CES0110063,

CES0130024

A88404

A91444

Fig. 20—Inserting Jumper Wire

OF2 OF1

OF2

OF1

TI DFT

TEST 30 50 90

DFT

HK32FA003/HK32FA006

A88403

CES0110063,

CES0130024

A91443

Fig. 21—Checking Between C and W2

13. Shut off unit power and reconnect fan lead.

TABLE 10—DEFROST CONTROL SPEED-UP TIMING SE-

14. Remove jumper between DFT and R terminals. Reconnect

defrost-thermostat leads. Failure to remove jumper causes

unit to switch to defrost every 30, 50, or 90 minutes and

remain in defrost for full 10 minutes.

QUENCE FOR CES0110063/CES0130024

SPEED-UP

(NOMINAL)

PARAMETER

MINIMUM

MAXIMUM

30-minute cycle

50-minute cycle

90-minute cycle

10-minute cycle

5 minutes

5.5

7 sec

15. Replace control-box cover. Restore power to unit.

12 sec

21 sec

2 sec

If defrost thermostat does not check out following above items or

incorrect calibration is suspected, check for a defective thermostat

as follows.

4.5

1 sec

1. Follow items 1-5 above.

4. Restart unit in heating.

2. Route sensor or probe underneath coil (or other convenient

location) using thermocouple temperature-measuring de-

vice. Attach to liquid line near defrost thermostat. Insulate

for more accurate reading.

5. Within a few minutes, liquid-line temperature drops within

a range causing defrost-thermostat contacts to close. Tem-

perature range is from 33°F to 27°F. Notice temperature at

which ohmmeter reading goes from ∞ to zero ohms.

Thermostat contacts close at this point.

3. Turn on power to outdoor unit.

—20—

6. Short between the speed-up terminals using a small, slotted

screwdriver.

3. Restart unit in heating mode, allowing frost to accumulate

on outdoor coil.

4. After a few minutes in heating mode, liquid-line tempera-

ture should drop below closing point of defrost thermostat

(approximately 30° F.

7. Unit changes over to defrost within 21 sec (depending on

timing-cycle setting). Liquid-line temperature rises to range

where defrost-thermostat contacts open. Temperature range

is from 75°F to 85°F. Resistance goes from zero to ∞ when

contacts open.

NOTE: Unit will remain in defrost until defrost thermostat

reopens at approximately 80° F coil temperature at liquid line or

remainder of defrost cycle time.

8. If either opening or closing temperature does not fall within

above ranges or thermostat sticks in 1 position, replace

thermostat to ensure proper defrost operation.

5. Turn off power to outdoor unit and reconnect fan-motor

lead to OF2 on control board after above forced-defrost

cycle.

CES0130024 DEFROST CONTROL

Compressor Shut Down

Some heat pumps built in 1993 and later incorporated a new

defrost control similar to the CES0110063 except the 5-minute

cycle protector has been removed. This control is used on heat

pump units with reciprocating compressors where short-cycle

protection is not required.

This control has the option of shutting down the compressor for 30

seconds while going into and out of defrost modes. This is

accomplished by turning DIP switch 3 to the ON position. See Fig.

22 for switch position. Factory default is in the OFF position.

Five-Minute Time Delay

Troubleshooting this control will be the same as the CES0110063

control except for the cycle-protector function. The CES0130024

control is identical to the CES0110063 except the T2 terminal and

cycle-protector logic have been removed.

This control has a 5–minute time delay on startup. The speedup

terminals can be used to bypass this delay. Momentary shorting

across the speedup terminals will, upon release, bypass 5–minute

time delay. Do not short out the speedup terminals for more than

5 seconds, or defrost mode will be initiated.

CES0130076 DEFROST CONTROL

This defrost control is the same size as the CES0130063 control

but is not backwards-compatible. (See Fig. 22.) To upgrade to the

new control, you must have replacement-defrost thermostat and

harness kit. See your replacement-component representative for kit

part number.

Troubleshooting

Troubleshooting this control is done in the same manner as the

CES0130063 control with the exceptions listed above.

DEFROST THERMOSTAT LOCATION

On most residential, outdoor heat-pump models, the defrost

thermostat is located on the return-bend side of the coil. The 5/16

OD feeder tube from the header will enter a 1–1/2 in. to 2–in. long

3/8 OD stub prior to entering the coil. There is only one stub tube

per coil. All other feeder tubes enter the coil directly. The defrost

thermostat attaches to this stub tube. (See Fig. 23.)

Defrost Settings

The defrost control is a time/temperature control which includes a

field-selectable time period (DIP switch 1 and 2 on board, see

Table 11) between defrost cycles of 30, 60, 90, and 120 minutes

(factory-set at 90 minutes).

X. FAN MOTORS

TABLE 11—DEFROST TIMER SETTINGS

Fan motor rotates the fan blade that either draws or blows air

through outdoor coil to perform heat exchange. Motors are totally

enclosed to increase reliability. This also eliminates need for rain

shield. For the correct position of the fan blade assembly, see Fig.

24 and Table 12.

SW1

SW2

Off

SW3

Off

120

WARNING: Turn off all power to unit before servicing

or replacing fan motor. Be sure unit main power switch is

turned off. Failure to do so may result in electric shock,

death, or injury from rotating fan blade.

To initiate a forced defrost, two options are available, depending

on the status of the defrost thermostat.

If defrost thermostat is closed, speedup pins (J1) must be shorted

by placing a Flathead screwdriver in between for 5 seconds and

releasing, to observe a complete defrost cycle. When the Quiet

Shift switch is selected, compressor will be turned off for two,

30–second intervals during this complete defrost cycle. When

Quiet Shift switch is in factory-default OFF position, a normal and

complete defrost cycle will be observed.

The bearings are permanently lubricated; therefore, no oil ports are

provided.

For suspected electrical failures, check for loose or faulty electrical

connections, or defective fan-motor capacitor. Fan motor is

equipped with thermal overload device in motor windings which

may open under adverse operating conditions. Allow time for

motor to cool so device can reset. Further checking of motor can

be done with an ohmmeter. Set scale on R X 1 position; check for

continuity between 3 leads. Replace motors that show an open

circuit in any of the windings. Place 1 lead of ohmmeter on each

motor lead. At same time, place other ohmmeter lead on motor

case (ground). Replace any motor that shows resistance to ground,

signs of arcing, burning, or overheating.

If defrost thermostat is in open position and speedup pins are

shorted (with a Flathead screwdriver) for 5 seconds and released,

a short defrost cycle will be observed (actual length is dependent

upon the selected Quiet Shift position). When Quiet Shift switch is

in ON position, the length of defrost is 1 minute (30 seconds

compressor-off period followed by 30 seconds of defrost with

compressor operation). On return to heat operation, compressor

will again turn off for an additional 30 seconds and the fan for 40

seconds. When the Quiet Shift is in OFF position, only a brief

30–second cycle will be observed.

XI. SERVICE ALARM CONTROL BOARD

NOTE: If the proper night-setback thermostat is not used, the

service-alarm control will work, but there will be no light

indication on thermostat.

The service-alarm control provides immediate warning when

outdoor heat pump requires servicing. It turns on indoor

thermostat-malfunction light if compressor does not operate for

If it is desirable to observe a complete defrost in warmer weather,

the thermostat must be closed as follows.

1. Turn off power to outdoor unit.

2. Disconnect outdoor fan-motor lead from OF2 on control

board. (See Fig. 22.) Tape to prevent grounding.

—21—

CESO130076–00

Speedup

Pins

Quiet

Shift

Defrost interval

DIP switches

A99442

Fig. 22—Defrost Control

either heating or cooling. This enables owner to obtain timely

heat-pump service during heating season, reducing supplementary

electric heat costs, and during cooling season, reducing period of

heat discomfort.

Service alarm requires 2 inputs.

1. It must sense a 24v input from thermostat. As thermostat

calls for heating or cooling, it supplies 24v to service-alarm

device.

2. A current transformer (or induction loop) similar to a

clamp-on ammeter senses current draw in the compressor

lead. Induction loop must sense a minimum current draw

when thermostat is calling for heating or cooling.

NOTE: On a single-phase compressor, induction loop senses

current in common leg. On a 3-phase compressor, induction loop

senses current in any 1 of the phases.

The service alarm is an accessory device. Service alarm locks out

compressor under certain adverse operating conditions. System is

manually reset by shutting it off at thermostat subbase, then

turning it back on. If adverse condition is corrected, system

restarts.

One example of an adverse condition would be a system located in

a desert climate where high operating temperatures may cause

system to shut down on the high-pressure switch or on the

compressor internal overload.

WARNING: If service alarm needs replacing, shut off

all power to unit before attempting removal. Electrical

shock can cause personal injury or death.

Connect service alarm to outdoor-unit control-circuit-terminal

board. (See Fig. 25 and wiring diagram on unit.)

Connect all field line-power wires to unit in usual manner. Route

1 field line-power supply wire through metallic loop on bottom of

service alarm then to normal unit connection. Units with RLA of

less than 14 amps will require 2 passes through the metallic loop.

Troubleshooting service-alarm device is easy. With thermostat

calling for heating or cooling and compressor running, indoor

thermostat light should be off. If on, check for wiring errors or

replace the service alarm.

To check for correct operation, shut off circuit breaker or discon-

nect switch to outdoor unit while it is running. Signal light on

thermostat should light. If this does not occur, check for wiring

errors or replace the service alarm.

Refer to Fig. 25 or 26 for wiring connections for service alarm or

service alarm with solid-state cycle-protector accessories, when

used.

NOTE: The wire from the X terminal on the service alarm to L on

the outdoor terminal board, indoor terminal board, and thermostat

subbase is field-supplied and wired when using defrost controls

HK32FA003 or HK32FA006. When defrost control CES0110063

or CES0130024 is used, field-supplied wire from X terminal on

service alarm to L on indoor thermostat subbase is required.

XII. OUTDOOR THERMOSTAT(S)

The outdoor thermostat(s) is installed in the control box. The

sensing bulb(s) remain in the control box. Outdoor thermostat

brings on stages of electric heat as outdoor temperature and

—22—

TABLE 12—FAN POSITION

AEROQUIET SYSTEM AND AEROMAX TOP

Dimension A (In.)

Fan Motor Part No.

HC29GE208

Fan Blade Part No.

Brookside

Revcor

—

LA01EB023

LA01EC019

LA01EA026

LA01RA015

LA01EW049

LA01RA015

4–5/32

5–1/8

—

4–5/8

—

HC31GE230/231

4–7/8

4–5/8

—

HC33GE208

HC33GE232

HC34GE231

HC34GE460

HC35GE208

5–1/4

4–29/32

4–17/32

LA01RA015

5–5/32

4–25/32

LA01EW048

LA01EA025

LA01RA024

LA01RA026

LA01EA025

LA01EW046

LA01EA031

LA01EC018

LA01RA026

LA01EA036

LA01EA024

LA01EC018

LA01EA036

LA01EC018

LA01RA026

LA01EA024

4–15/16

5–7/8

—

HC35GE232

5–11/32

5–9/16

6–1/8

5–3/32

4–11/16

6–1/8

—

HC37GE208

HC37GE230

HC38GE221

6–5/32

7–25/32

5–11/16

5–1/2

—

HC39GE232

HC39GE234

HC39GE461

4–3/4

—

5–9/16

5–3/32

5–1/2

4–27/32

—

6–1/16

6–1/4

—

6–1/16

5–9/32

5–27/32

5–7/32

5–11/32

5–19/32

HC40GE230

HC40GE461

FEEDER TUBE

STUB TUBE

DEFROST

THERMOSTAT

A97517

Fig. 23—Defrost Thermostat Location

BASKET TOP

A91428

Fig. 24—Fan Position

—23—

HIGH AND/OR LOW PRESSURE

AND/OR DISCHARGE TEMPERATURE

SWITCH (IF USED)

DTS

24-VOLT WIRING

HPS

LPS

BRN

BLU

BLU YEL

YEL

BLK

ORN

YEL RED

THERMOSTAT

SUBBASE

INDOOR

UNIT

TERMINAL

BOARD

OUTDOOR

UNIT

TERMINAL

BOARD

SERVICE ALARM

PASS SUPPLY WIRE THROUGH

METALLIC LOOP TWICE ON

UNITS WITH NAMEPLATE

RLA OF 14 AMPS OR LESS.

*METALLIC

LOOP

ONE FIELD

LINE VOLTAGE

SUPPLY WIRE

A88340

Fig. 25—Service Alarm Wiring Connections

FIELD LINE VOLTAGE SUPPLY WIRE

CYCLE PROTECTOR

T1 T2 T3

SERVICE ALARM

YEL

HIGH AND/OR LOW PRESSURE

AND/OR DISCHARGE TEMPERATURE

SWITCH (IF USED)

VIO BLK

ORN

DTS

YEL

BLU

BLK

LPS

HPS

BLK

BRN

A88339

THERMOSTAT INDOOR OUTDOOR

SUBBASE UNIT

UNIT

TERMINAL TERMINAL

BOARD

COMMON POTENTIAL

FACTORY WIRING (FIELD CONNECTED)

FIELD-SUPPLIED WIRING

CONTACTOR

A88339

Fig. 26—Wiring Connections for Service Alarm and Cycle Protector

heat-pump output drops. Setting at which thermostat closes is

variable, depending on design of system. It is set at time of

installation and should not be changed without cause. Up to 2

outdoor thermostats may be installed. Some systems may not have

any thermostat. An outdoor thermostat can also be used to lock out

compressor operation at low ambients in condensing unit not

equipped with low-ambient control.

XIII. COMPRESSOR PLUG

The compressor electrical plug provides a quick-tight connection

to the compressor terminals. The plug completely covers the

compressor terminals, and the mating female terminals are com-

pletely encapsulated in the plug. Therefore, the terminals are

isolated from any moisture so corrosion and resultant pitted or

discolored terminals are reduced. The plug is oriented to the relief

slot in the terminal box so the cover cannot be secured if wires are

not positioned in slot, assuring correct electrical connection at the

compressor. The plug can be removed by simultaneously pulling

while ″rocking″ the plug. However, these plugs are specialized and

vary in terminal orientation in the plug. Therefore, plugs can be

used on only the specific compressor or group as shown in Fig. 27.

Although these devices are installed in control circuit (24v), turn

off all power to unit before attempting to troubleshoot thermostat.

Use a standard ohmmeter to check for continuity through thermo-

stat. If you suspect thermostat is out of calibration, use calibrated

electronic thermometer to determine correct outdoor temperature.

Turn thermostat dial knob until switch closes. Observe this using

ohmmeter across switch. Read temperature setting when switch

closes. It should be close to reading observed using electronic

thermometer. Any setting within ± 5°F is acceptable.

For the Carlyle and Bristol compressors in Fig. 27, the triangle

formed by the fusite terminals points down, and the plug is

likewise oriented. The fusite terminals and plug-terminal orienta-

—24—

tion shown for the Tecumseh compressor is shown with the

triangle formed by the terminals pointing toward the top. The

configuration around the fusite terminals is the outline of the

terminal covers used on the specific compressors. The slot through

which the wires of the plug are routed is oriented on the bottom or

slightly to the left or right. The correct plug can be connected

easily to the compressor terminals and plug wires routed easily

through the slot in the terminal cover. Therefore, if a Carlyle or

Bristol compressor is substituted for a Tecumseh compressor, a

new plug must be installed. If the plug is not changed, proper

connection and routing of the plug wires through the terminal

cover will be impossible.

G—Energizes blower circuit from indoor thermostat.

E—Energizes emergency-heat relay.

W2—Energizes first-stage supplemental heat through defrost relay

(wht).

L—Energizes light on thermostat with service alarm.

W3—Energizes second- or third-stage supplemental heat.

R—Energizes 24v power from transformer (red).

Y—Energizes contactor for first-stage cooling or first-stage heat-

ing for heat pumps (yel).

O—Energizes reversing valve on heat pumps (orn).

C—Common side of transformer (blk).

RECIPROCATING COMPRESSOR

BRISTOL

COPELAND

CARLYLE

LEAD 3

BLUE

The compressor is the heart of the refrigeration system. It pumps

refrigerant through the system. If it malfunctions, system capacity

and efficiency could be negatively affected.

CAUTION: The compressor is an electrical (as well as

mechanical) device. Exercise extreme caution when

working near compressors. Power should be shut off, if

possible, for most troubleshooting techniques. Refriger-

ants in system present other safety hazards. Always wear

safety glasses and gloves when handling refrigerants.

LEAD 2

YEL.

LEAD 1

BLK.

TECUMSEH

Compressor failures are classified in 2 broad failure categories:

mechanical and electrical. Both types are discussed below.

LEAD 1

BLK.

I. MECHANICAL FAILURES

A compressor is a mechanical pump driven by an electric motor

contained in a welded or hermetic shell. In a mechanical failure,

motor or electrical circuit appears normal, but compressor does not

function normally.

LEAD 2

YEL.

LEAD 3

BLUE

CAUTION: Exercise extreme caution when reading

compressor currents when high-voltage power is on.

Correct any of the problems described below before

installing and running a replacement compressor. Wear

safety glasses and gloves when handling refrigerants.

TECUMSEH

LEAD 1

BLK.

LEAD 3

BLUE

LOCKED ROTOR

In this type of failure, compressor motor and all starting compo-

nents are normal. When compressor attempts to start, it draws

locked-rotor current and cycles off on the internal protection.

Locked-rotor current is measured by applying a clamp-on ammeter

around common (blk) lead of the compressor on a single-phase

compressor, or any 1 of the leads on a 3-phase compressor. Current

drawn when it attempts to start is then measured. LRA (locked-

rotor amp) value is stamped on compressor nameplate.

LEAD 2

YEL.

MILLENNIUM

If compressor draws locked-rotor amps and all other external

sources of problems have been eliminated, compressor must be

replaced. Because compressor is a sealed unit, it is impossible to

determine exact mechanical failure. However, complete system

should be checked for abnormalities such as incorrect refrigerant

charge, restrictions, insufficient airflow across indoor or outdoor

coil, and so forth, which could be contributing to the failure.

LEAD 1

BLK.

LEAD 3

BLUE

RUNS, DOES NOT PUMP

LEAD 2

YEL.

In this type of failure, compressor motor runs and turns compres-

sor, but compressor does not pump the refrigerant. A clamp-on

ammeter on common leg of a single-phase compressor, or any 1

lead of a 3-phase compressor, shows a very low current draw,

much lower than RLA (rated load amps) value stamped on

compressor nameplate. Because no refrigerant is being pumped,

there is no return gas to cool compressor motor. It eventually

overheats and shuts off on its internal protection.

A94002

Fig. 27—Compressor Plug

XIV. LOW-VOLTAGE TERMINALS

The low-voltage terminal designations, along with descriptions

and/or functions, are used on all split-system condensers and heat

pumps:

RUNS, DOES NOT PUMP, HIGH-TO-LOW SIDE LEAK

—25—

(EXAMPLE)

TO DETERMINE INTERNAL CONNECTIONS OF SINGLE-

PHASE MOTORS (C,S,R) EXCEPT SHADED-POLE

DEDUCTION:

POWER OFF!

(GREATEST RESISTANCE)

RUN WINDING (R)

5.8Ω (OHM)

START WINDING (S)

OHMMETER

(SMALLEST RESISTANCE)

IS COMMON (C)

BY ELIMINATION

0-10Ω SCALE

0.6Ω

(REMAINING RESISTANCE)

IS COMMON,

THEREFORE,

5.2Ω

5.8Ω

0.6Ω

START WINDING (S)

IS RUN WINDING (R)

A88344

Fig. 28—Identifying Internal Connections

In this type of failure, compressor motor runs and turns compres-

sor, and compressor is pumping. Usually, an internal problem such

as blown head gasket or broken internal-discharge line causes

compressor to pump hot discharge gas back into its own shell

rather than through system.

2. Remove and recover all refrigerant from system so that

gage pressures are 0 psi.

3. Clean area around leak to bare metal.

4. Apply flux and repair joint with silver solder. Do not use

low-temperature solder such as 50-50.

Using pressure gages on service valves shows high suction and

low discharge pressure readings. Motor currents are lower than

normal. Because hot gas is being discharged into shell, the shell

becomes hot. The hot gas causes compressor motor to cycle off on

its internal protection.

5. Clean off excess flux, check for leaks, and apply paint over

repaired area to prevent corrosion.

Do not use this method to repair a compressor leak due to severe

corrosion. Never attempt to repair a compressor leaking at electric

terminals. This type of failure requires compressor replacement.

RUNS AND PUMPS, LOW CAPACITY

II. ELECTRICAL FAILURES

This failure type is difficult to pinpoint because extent of damage

varies. Compressor is a pump with internal valves that enable

compressor to pump properly. The cylinder has a set of suction and

discharge valves. Any of these parts may become damaged or

broken, causing loss in pumping capacity. Severity of damage

determines amount of capacity loss. Use pressure gages to find any

abnormal system pressures if system charge and other conditions

are normal.

The compressor mechanical pump is driven by an electric motor

within its hermetic shell. In electrical failures, compressor does not

run although external electrical and mechanical systems appear

normal. Compressor must be checked electrically for abnormali-

ties.

Before troubleshooting compressor motor, review this description

of compressor motor-terminal identification.

SINGLE-PHASE MOTORS

An owner may complain that a unit is not handling the building’s

heating or cooling load. The compressor current draw may be

abnormally low or high. Although this type of failure does occur,

all other possible causes of capacity loss must be eliminated before

condemning compressor.

To identify terminals C, S, and R:

1. Turn off all unit power.

2. Short the run and start capacitors to prevent shock.

3. Remove all wires from motor terminals.

NOISY COMPRESSOR

4. Read resistance between all pairs of terminals using an

ohmmeter on 0-10 ohm scale.

Noise may be caused by a variety of internal problems such as

loosened hardware, broken mounting springs, etc. System prob-

lems such as overcharged compressor (especially at start-up) or too

much oil in compressor may also cause excessive noise. Excess oil

in compressor is normally encountered only after a replacement

compressor has been added without purging oil from previous

compressor. As new compressor pumps, excess oil in system

returns and adds to volume already present, causing noise.

5. Determine 2 terminals that provide greatest resistance

reading.

Through elimination, remaining terminal must be common (C).

Greatest resistance between common (C) and another terminal

indicates start winding because it has more turns. This terminal is

start (S). Remaining terminal will be run winding (R). (See Fig.

28.)

COMPRESSOR LEAKS

NOTE: If compressor is hot, allow time to cool and internal line

break to reset. There is an internal line-break protector which must

be closed.

CAUTION: Use safety glasses and gloves when han-

dling refrigerants.

THREE-PHASE MOTORS

Resistance readings between all 3 sets of windings should be the

same.

Sometimes a leak is detected at weld seam around girth of

compressor or a fitting that joins compressor shell. Many of these

leaks can be repaired and the compressor saved if correct proce-

dure is followed.

All compressors are equipped with internal motor protection. If

motor becomes hot for any reason, protector opens. Compressor

should always be allowed to cool and protector to close before

troubleshooting. Always turn off all power to unit and disconnect

leads at compressor terminals before taking readings.

1. Turn off all power to unit.

—26—

Most common motor failures are due to either an open, grounded,

or short circuit. Directions below are specifically for single-phase

units, however, they also apply to 3-phase compressors. When a

single-phase compressor fails to start or run, 3 tests can help

determine the problem. First, all possible external causes should be

eliminated, such as overloads, improper voltage, pressure equal-

ization, defective capacitor(s), relays, wiring, and so forth. Com-

pressor has internal line-break overload, so be certain it is closed.

4. Motor must be dry or free from direct contact with liquid

refrigerant.

MAKE THIS CRITICAL TEST

(Not advisable unless above conditions are met.)

1. Be sure all power is off.

2. Discharge all capacitors.

3. Remove wires from terminals C, S, and R.

OPEN CIRCUIT

4. Place instrument probes together and determine probe and

lead wire resistance.

To determine if any winding has a break in the internal wires and

current is unable to pass through:

5. Check resistance readings from C-R, C-S, and R-S.

1. Be sure all power is off.

6. Subtract instrument probe and lead resistance from each

reading.

2. Discharge all capacitors.

3. Remove wires from terminals C, S and R.

If any reading is within ± 20 percent of known resistance, motor is

probably normal. Usually a considerable difference in reading is

noted if a turn-to-turn short is present.

4. Check resistance from C-R, C-S and R-S using an ohmme-

ter on 0-1000 ohm scale.

Because winding resistances are usually less than 10 ohms, each

reading appears to be approximately 0 ohm. If resistance remains

at 1000 ohms, an open or break exists, and compressor should be

replaced.

III. SYSTEM CLEANUP AFTER BURNOUT

CAUTION: Turn off all power to unit before proceed-

ing. Wear safety glasses and gloves when handling

refrigerants. Acids formed as a result of motor burnout

can cause burns.

CAUTION: Be sure internal line-break overload is not

temporarily open.

NOTE: To analyze level of suspected contamination from com-

pressor burnout, use Total Test. See your distributor/branch.

GROUND CIRCUIT

To determine if a wire has broken or come in direct contact with

shell, causing a direct short to ground:

Some compressor electrical failures can cause motor to overheat.

When this occurs, by-products, which include sludge, carbon, and

acids, can contaminate system. If burnout is severe enough, system

must be cleaned before replacement compressor is installed. The 2

types of motor burnout are classified as mild or severe.

1. Be sure all power is off.

2. Discharge all capacitors.

3. Remove wires from terminals C, S, and R.

In mild burnout, there is little or no detectable odor. Compressor

oil is clear or slightly discolored. An acid test of compressor oil

will be negative. This type of failure is treated the same as

mechanical failure. Liquid-line strainer should be removed and

liquid-line filter drier installed.

4. On hermetic compressors, allow crankcase heaters to re-

main on for several hours before checking motor to ensure

windings are not saturated with refrigerant.

5. Use an ohmmeter on R X 10,000 ohm scale. A megohm-

meter may be used in place of ohmmeter. Follow manufac-

turer’s instructions.

In a severe burnout, there is a strong, pungent, rotten-egg odor.

Compressor oil is very dark. Evidence of burning may be present

in tubing connected to compressor. An acid test of compressor oil

will be positive. Complete system must be reverse flushed with

refrigerant. Check-Flo-Rater™ or TXV must be cleaned or re-

placed. In a heat pump, accumulator and reversing valve are

replaced. These components are also removed and bypassed during

reverse-flushing procedure. Remove and discard liquid-line

strainer. After system is reassembled, install liquid-line and

suction-line filter driers. Run system for 2 hrs. Discard both driers

and install new liquid-line drier only.

6. Place 1 meter probe on ground or on compressor shell.

Make a good metal-to-metal contact. Place other probe on

terminals C, S, and R in sequence.

7. Note meter scale.

8. If reading of zero or low resistance is obtained, motor is

grounded. Replace compressor.

A 1 ton or less capacity compressor is probably grounded if

resistance is below 1 million ohms. On larger-sized, single-phase

compressors, resistance to ground should not be less than 1000

ohms per volt of operating voltage.

IV. COMPRESSOR REMOVAL AND REPLACEMENT

Once it is determined that compressor has failed and the reason

established, compressor must be replaced.

Example:

230 volts X 1000 ohms/volt = 230,000 ohms minimum.

SHORT CIRCUIT

CAUTION: Wear safety glasses and gloves when han-

dling refrigerants and when using brazing torch.

To determine if any wires within windings have broken through

their insulation and made contact with other wires, thereby

shorting all or part of the winding(s), be sure the following

conditions are met:

1. Shut off all power to unit.

1. Correct motor-winding resistances must be known before

testing, either from previous readings or from manufactur-

er’s specifications.

2. Remove and recover all refrigerant from system until

pressure gages read zero psi. Use all service ports.

3. Disconnect electrical leads from compressor. Disconnect or

remove crankcase heater and remove compressor-holddown

bolts.

2. Temperature of windings must be as specified, usually

about 70°F.

3. Resistance-measuring instrument must have an accuracy

within ± 5 to 10 percent. This requires an accurate ohmme-

ter, such as a Wheatstone bridge or null balance-type

instrument.

4. Cut compressor from system with tubing cutters. Do not use

brazing torch for compressor removal. Oil vapor may ignite

when compressor is disconnected.

—27—

5. Scratch matching marks on stubs in old compressor. Make

corresponding marks on replacement compressor.

6. Use torch to remove stubs from old compressor and to

reinstall them in replacement compressor.

Scroll Gas Flow

Compression in the scroll is

created by the interaction of

an orbiting spiral and a

stationary spiral. Gas enters

an outer opening as one of the

spirals orbits.

7. Use copper couplings to tie compressor back into system.

8. Evacuate system, recharge, and check for normal system

operation.

9. Copeland CR-6 and scroll compressors have copper-plated,

steel-suction ports. Excess heat during brazing will burn off

copper plating. See Brazing section for additional informa-

tion.

COPELAND SCROLL COMPRESSOR

I. FEATURES

The scroll compressor pumps refrigerant through the system by the

interaction of a stationary and an orbiting scroll. (See Fig. 29.) The

scroll compressor has no dynamic suction or discharge valves, and

it is more tolerant of stresses caused by debris, liquid slugging, and

flooded starts. Due to the design of the scroll compressor, the

internal compression components unload (equalize pressure) on

shutdown. The white oil (Sontex 200LT) used in the scroll is

compatible with 3GS oil, which can be used if additional oil is

required. (See Table 13 for oil recharge requirements.)

As the spiral continues to orbit,

the gas is compressed into an

increasingly smaller pocket.

The open passage is sealed off

as gas is drawn into the spiral.

TABLE 13—COMPRESSOR OIL RECHARGE

By the time the gas arrives at

the center port, discharge

pressure has been reached.

Actually, during operation, all

six gas passages are in various

stages of compression at all

times, resulting in nearly con-

tinuous suction and discharge.

RECHARGE

(FL. OZ.)

COMPRESSOR MODEL

OIL TYPE

Carlyle/Scroll

″J″ Type

SC, SRD450AC

Suniso 3GS

Zerol 150

w/3 percent

Syn-O-Ad

A90198

SRH482, SRY482

SRH602, SRY602

Fig. 29—Scroll Compressor Refrigerant Flow

vacuum. If a pumpdown procedure is used, the scroll compressor

is capable of pumping into a vacuum very quickly, which could

cause fusite arcing and compressor failure. See Step IV of

Reciprocating Compressor section for removal and replacement.

Copeland

CRG3, CRH3, CRJ3, CRK3, CRL3

CRN5, CRP5, CRT5, CTH1, CTL1

CRC4, CRZ4

III. DISCHARGE THERMOSTAT

CR16K6 THROUGH CR42K6

*ZR18K1

Some scroll compressors have a discharge thermostat that recip-

rocating compressors do not have. This thermostat is mounted in a

well in the top of the compressor shell to sense if the discharge

temperature reaches 290°F and shuts down the compressor to

prevent damage to it. When the temperature of the thermostat

reaches 140°F, power is restored to the compressor.

To determine if the thermostat is operating properly, either attach

the thermocouple of an electronic thermometer to the dome of the

compressor near the thermostat, or remove the thermostat and

place the thermocouple inside the well. The electronic thermom-

eter must be capable of reading at least 300°F. Start the unit and let

it run for at least 15 minutes to obtain normal operating conditions.

Watch the thermometer to see if it is approaching 270°F. If the

thermocouple is located on the dome near the discharge thermo-

stat, there could be a 20° difference between well and dome

temperatures. If the temperature approaches 270°F, repair system

problem, such as low charge, blocked condenser coil, and so forth.

If the temperature does not approach 270°F, replace discharge

thermostat.

*ZR23K1, ZR28K1

*ZR34K1

Suniso 3GS

*ZR40K1

*ZR49K1-PFV

*ZR49K2-TF5, ZR49K2-TFD

*ZR61K2-PFV

*ZR61K2-TF5, ZR61K2-TFD

Tecumseh

AV55

AW55

Suniso 3GS

Bristol

H23A

H23B

H24A3, H24A4

H24A5

H25A, H26A

Replacing Discharge Thermostat

H25B, H26B, H29B

To replace the discharge thermostat, refer to the Installation

Instructions packaged with the replacement discharge thermostat

kit. (See Fig. 30.)

*Copeland scrolls are charged initially with Sontex 200LT white oil. Since this

oil is not commercially available, use 3GS.

II. TROUBLESHOOTING

IV. DISCHARGE SOLENOID VALVE

Troubleshooting mechanical or electrical problems in a scroll

compressor is the same as for a reciprocating compressor, except

that a scroll compressor should never be allowed to pump into a

Some larger units equipped with scroll compressors contain a

solenoid valve that is piped between the discharge tube and suction

tube of the compressor. The purpose of the solenoid valve is to

—28—

The scroll compressor is capable of pumping into a vacuum very

quickly, which could cause fusite arcing and compressor failure.

See Step IV of Reciprocating Compressor section for removal and

replacement.

PLASTIC CAP

IV. SCROLL COMPRESSOR, 3–PHASE MONITOR

CES0130075 — PHASE MONITOR

BLUE SEALANT

PRONG

This control is factory-installed on all 3–phase, scroll compressor

models. (See Fig. 31 and 32.) On start-up, the control will energize

the pilot relay for 2 seconds. The monitor will check for correct

compressor rotation. If rotation is correct, unit will continue to run.

If rotation is incorrect, the control will break the 24vac power at

the contactor and an LED light on the control will flash. If LED is

flashing, turn off power, reverse L1 and L3 field-power leads, and

restart unit. This control will check incoming power at every

restart.

GROMMET

TWO-SPEED SYSTEM

I. CAUTIONS AND WARNINGS

CAUTION: For proper unit operation and reliability, the

2-speed units must be installed with the factory-supplied

balance port, hard shutoff TXV. Do not install with

indoor coils having piston or capillary-tube metering

devices.

THERMOSTAT

A90198

THERMAL GREASE

CAUTION: Do not install equivalent interconnecting

tubing lengths greater than 100 ft. Do not decrease or

increase interconnecting tubing diameters.

Fig. 30—Location of Discharge Thermostat

cause a rapid pressure equalization around the compressor, thus

reducing the normal shutdown sound created by reverse rotation of

the scroll. The solenoid valve is normally closed and is wired

across high-voltage line 1 to load terminals of the contactor. (See

Fig. 18.) The solenoid-valve assembly also requires a check valve

piped in the discharge tube between the solenoid-valve tee and the

condenser coil, or reversing valve on heat pumps. The purpose of

the check valve is to prevent refrigerant from bypassing through

the solenoid valve into the suction tube when the unit cycles off.

CAUTION: To avoid electrical shock, bleed resistor

must be connected across run capacitor. Replace if

missing or damaged.

CAUTION: Contactor is mechanically interlocked. Do

not disable mechanical interlock. Compressor damage

may occur.

MILLENNIUM SCROLL COMPRESSOR

I. FEATURES

The scroll compressor pumps refrigerant through the system by the

interaction of a stationary and an orbiting scroll. (See Fig. 29.) The

scroll compressor has no dynamic suction or discharge valves, and

it is more tolerant of stresses caused by debris, liquid slugging, and

flooded starts. The Millennium scroll varies from the Copeland

scroll in that the Millennium has a shutdown flapper valve located

between the scroll plates and the discharge head, whereas the

Copeland has a check device at the discharge connection after the

discharge head. The Copeland discharge head unloads when the

compressor shuts down. The scroll plate actually runs backwards

while it unloads. A 1 to 3 second unloading of refrigerant occurs.

WARNING: Contactor control voltage is 240vac.

WARNING: Do not attempt to operate this equipment

below 55°F outdoor ambient temperature.

NOTE: Sections that follow describe the 598A Series B and

698A Series B products, which started production March, 1994.

For 598A Series A and 698A Series A products, refer to the

Split-System Service Manual dated 3–1–94, Catalog No. BDP

3356–115.

The Millennium flapper valve eliminates the refrigerant unloading

by not allowing the discharge head to run backwards because of its

location. The Millennium scroll compressor uses Zerol 150 oil

with 3 percent Syn-O-Ad and is the only oil recommended for oil

recharge. See Table 13 for recharge requirements.

II. SYSTEM FUNCTIONS

II. COMPRESSOR PROTECTION

COOLING OPERATION

Millennium scroll compressors are protected by an internal line-

break mounted on the motor windings. Internal protectors respond

to overcurrent and high temperature. These protectors are

automatic-reset devices containing a snap-action, bi-metal switch.

The 2-speed products utilize a 2-stage-cooling indoor thermostat.

With a call for first-stage cooling (Y1), the outdoor fan and

low-speed compressor are energized. If low speed cannot satisfy

the cooling demand, high speed will be energized (Y1 and Y2) by

the second stage of the indoor thermostat. The thermostat has a 2°

differential between first and second stages. After second stage is

satisfied, the unit returns to low-speed operation, until first stage is

satisfied, or until second stage is again required.

III. TROUBLESHOOTING

Troubleshooting mechanical and electrical problems in a scroll

compressor is similar to a reciprocating compressor, except that a

scroll compressor should never be allowed to pump into a vacuum.

—29—

A00010

Fig. 31—CES0130075 3–Phase Monitor Board

COMP

CONT

EQUIP

GND

*CH

CONT

CAP

OFM

LOGIC

CESO130075

CONT

*LPS

*HPS

LOGIC

*LLS

CTD

IFR

INDOOR

THERMOSTAT

EXTERNAL POWER SUPPLY 24 V

A00011

Fig. 32—CESO130075 3–Phase Monitor Wiring Diagram

—30—

HEATING OPERATION (HEAT PUMP ONLY)

LM1 LM2 DFT1 DFT2 T1 T2 S2 S1 PW2 PW1

The 2-speed products utilize a 2-stage-heating indoor thermostat.

The first stage of heating is heat-pump operation (Y1). Auxiliary

backup heat is controlled by second stage (W2). There is a 2°

differential between first and second stage. The control board

determines the compressor speed based on ambient temperature.

See Table 14 for ambient temperatures at which speed changes

occur. When high-speed, heat-pump heating is required, the

control provides a Y2 (24vac) signal back to the thermostat to

energize high-speed-indicator LED.

FURN INT

OFF

SPEED-UP

TABLE 14—AMBIENT TEMPERATURE FOR HIGH- AND

LOW-SPEED OPERATION

AMBIENT TEMPERATURE (°F)

UNIT

SIZE

STAGE 2 DEFROST BALANCE

LATCH TIME POINT

High Speed

30 or less

33 or less

40 or less

Low Speed

31 or greater

34 or greater

41 or greater

036

048

060

A93568

Fig. 34—Speedup Terminals

CRANKCASE-HEATER OPERATION

LED FUNCTION LIGHTS

When using the factory-authorized indoor thermostats with the

2-speed outdoor units, there are 2 locations where system-function

LED-indicator lights are available. The indoor thermostat provides

indicator lights for high- and low-speed operation, system mal-

function, and auxiliary heat for heat pumps. The 2-speed control

board has an LED which provides signals for several system

operations. See Table 15 for LED functions, indicator locations,

and definitions. Table 15 also provides the order of signal

importance if more than 1 signal should occur. The signal to the

indoor thermostat is supplied by the low-voltage ″L″ lead.

The 2-speed control energizes the crankcase heater during the

unit’s off cycle when the outdoor ambient is below 75°F.

OUTDOOR FAN-MOTOR OPERATION

The 2-speed control energizes the outdoor fan any time the

compressor is operating. The outdoor fan remains energized during

the 1-minute, speed-change time delay and if a pressure switch or

compressor PTC overload should trip.

If the outdoor fan motor won’t run, check the header-pin housing.

(See Fig. 37.) There should be NO jumper wire between Terminals

15 and 16.

THREE-SECOND TIME DELAY

Any time the control receives a 24v input, such as Y1 or Y2, there

is a 3-sec time delay before the control function is initiated. This

helps prevent nuisance trips and thermostat ″jiggling.″

Heat Pumps

After the termination of a defrost cycle, the outdoor fan delays

come on for 20 sec. This allows the refrigeration system to recover

the outdoor coil heat and minimize the ″steam cloud″ effect.

ONE-MINUTE SPEED-CHANGE TIME DELAY

When the compressor changes speeds from high to low or low to

high, there is a 1-minute time delay before the compressor restarts.

The outdoor fan motor remains running.

SECOND-STAGE LATCHING

When low-speed cooling operation no longer satisfies the first

stage of the indoor thermostat, the indoor temperature will increase

by 2° until second stage is energized. After high-speed cooling

satisfies second stage, it returns to low-speed cooling operation. If

desired, the installer may select to have high-speed cooling by

energizing Y1. High speed will stay energized until Y1 is satisfied.

This eliminates the temperature drop between the first and second

stages of indoor thermostat, holding room temperature closer to set

point.

FIVE-MINUTE TIME DELAY

The 2-speed-control logic contains a 5-minute time delay that

prevents the unit from short cycling after a thermostat-off cycle or

power interruption. The unit can be forced to operate immediately

by momentarily touching a jumper between the speed-up terminals

of the control board. (See Fig. 33 and 34.) The speed-up feature

will not bypass any other function or time delay.

To utilize this function, the unit capacity should be plotted versus

the heat gain of the structure, which provides the system’s balance

point when the structure requires high-speed capacity. (See Fig.

35.)

HIGH VOLTAGE

LOW VOLTAGE

CCH ODF

LM1 LM2 DFT1 DFT2 T1 T2 S2 S1 PW2 PW1

Second-stage latching can be selected by rotating the potentiom-

eter (POT) to the desired outdoor second-stage latching tempera-

ture (See Fig. 34.) The temperatures that can be selected are 85°,

90°, 95°, 100°, and 105°F. The POT is factory set at 105°F.

FURN INT

OFF

SPEED-UP

ZONE SELECTION

STAGE 2 DEFROST BALANCE

LATCH

TIME

POINT

If the stage–2 latch POT is set to ZONE position, the compressor

operating speed in either heat or cool mode is determined by the

Y1 and/or Y2 inputs. The system operates in low speed with a Y1

input and high speed with Y2 or Y1-and-Y2 input. This allows the

multistage-zoning system to determine what speed is needed

regardless of outdoor temperature or switchover point.

LED 1

A93569

Fig. 33—Two-Speed Control Board

TWO-MINUTE LOW-SPEED MINIMUM

DEFROST TIME SELECTION

The defrost interval can be field selected, depending on local or

geographic requirements. It is factory set at 90 minutes and can be

changed to either 30 or 50 minutes by rotating the defrost-time

POT. (See Fig. 34.)

If the unit has not operated within the past 30 minutes, the unit

operates for a minimum of 2 minutes in low speed upon the next

thermostat high or low demand.

—31—

TABLE 15—FUNCTION LIGHT CODE AND DISPLAY LOCATION

CODE

T’STAT

UNIT

DEFINITION

POSSIBLE CAUSE

Constant flash

No pause

No demand

Stand by

—

1 flash

w/pause

—

Low-speed operation

High-speed operation

Ambient thermistor failure

Coil thermistor failure

—

2 flashes

w/pause

3 flashes

w/pause

4 flashes

w/pause

Thermistor drift, wrong location

Incorrect wiring

Incorrect refrigerant charge

Dirty indoor/outdoor coil

3 flashes

pause

4 flashes

Thermistor out of range**

Dirty outdoor coil

Refrigerant overcharge

Wrong indoor coil

5 flashes

w/pause

Pressure switch trip

(LM1/LM2)

X‡

Low refrigerant charge

Compressor mechanical problem

Dirty indoor/outdoor coil

6 flashes

w/pause†

Compressor PTCs out of limit

Board failure

Constant light

No pause

Equipment or electrical service

not grounded

No flash

*Function light signals order of importance; in case of multiple-signal request, 1 is most important.

†Signal at thermostat will occur after 3 consecutive attempted restarts and lockout has occurred.

‡Will be energized if pressure switch remains open for 1 hr.

**Check both thermistors to determine which is faulty.

FIELD-INITIATED FORCED DEFROST

By placing a jumper across the speedup terminals for a minimum

of 5 sec and then removing it, the unit initiates a defrost cycle. (See

Fig. 34.) The cycle occurs only if the outdoor ambient is less than

50°F, regardless of outdoor coil temperature. The cycle terminates

when the coil thermistor reaches 80°F ( ± 5) or the defrost period

reaches a maximum of 10 minutes.

HIGH SPEED

BALANCE POINT

FURNACE INTERFACE

This feature provides a heat-pump lockout upon a demand for

auxiliary heat (W2) and must be used when interfacing a heat

pump with a gas/oil furnace. Field selection of the furnace-

interface option is done by connecting the factory-supplied jumper

to the ON position of the 3 terminal connectors. (See Fig. 33.)

When the option is selected, the heat pump will be locked out of

operation any time there is a thermostat demand for W2 or the

outdoor ambient is below the balance-point POT-setting selection.

(See Fig. 34.) When the unit requires defrost, auxiliary heat (W2)

energizes the furnace. After defrost is terminated, the heat pump

shuts down and the furnace satisfies the thermostat. To utilize this

function, the economic and/or thermal balance point must be

determined. See the appropriate heat pump balance-point work-

sheet available from your distributor or branch.

STRUCTURE

BALANCE POINT

LOW SPEED

BALANCE POINT

100

110

120

TEMPERATURE (°F)

A91282

BALANCE POINT

Fig. 35—Typical Cooling Balance Points

DEFROST

This feature can be used in 2 different options: furnace interface or

electric-heat staging. Refer to the Furnace Interface section for its

application. If the heat pump is installed with a fan coil with

multistages of electric heat, this option can be used to stage the

banks of heat by outdoor ambient. This eliminates the need for

accessory outdoor thermostats.

When using this option to stage electric heat, first stage is

energized by a W2 demand, and second stage is energized by a W3

demand. Select the W3 desired temperature by rotating the

balance-point POT. (See Fig. 34.) Temperatures that may be

selected are 10°, 15°, 20°, 25°, 30°, 35°, 40°, and 45°F. The POT

is factory set at 45°F.

LOW-SPEED HEATING WITH AUXILIARY HEAT

If the system is operating in low-speed heating and there is a

demand for auxiliary heat (W2), the system changes to high-speed

operation. W2 is energized unless the low-voltage control wiring is

configured as described in Fig. 36.

The 2-speed control logic for the defrost function is the standard

time and temperature initiated, time or temperature terminated.

Defrost occurs only at outdoor temperatures less than 50°F. The

control initiates defrost when the outdoor coil thermistor is 30°F (±

2) or less, and the selected defrost time (interval) has been

accumulated during unit operation. Termination occurs when the

coil thermistor reaches 80°F (± 5) or the defrost period reaches a

maximum of 10 minutes.

Defrost always occurs in high speed unless the stage–2 latch POT

is set at ZONE. During defrost the unit operates in high speed,

energizes the reversing valve (O) and auxiliary heat (W2), and

de-energizes the outdoor fan. Upon termination, there is a 20-sec

delay in the outdoor fan being energized. If the stage–2 latch POT

is set to ZONE and the heat pump is in low speed, it defrosts in low

speed.

—32—

PRESSURE SWITCH PROTECTION

TWO SPEED

THERMOSTAT

FAN

COIL

TWO SPEED

HEAT PUMP

The outdoor unit is equipped with high- and low-pressure

switches, wired in series. If a pressure switch opens, the control

provides a 5-minute time delay in outdoor unit operation with the

outdoor fan running. A malfunction signal appears on the control

when a pressure switch opens. If the switch remains open for 1 hr

or longer, a malfunction signal is provided at the L terminal of the

indoor thermostat.

CONTROL

LOGIC

A93572

III. FACTORY DEFAULTS

Fig. 36—Low-Voltage Control Wiring

AUXILIARY HEAT (W2) LOCKOUT

Factory defaults have been provided in the event of failure of the

ambient thermistor, outdoor-coil thermistor, and/or furnace inter-

face jumper. Refer to Table 17 for default and function.

In some areas, it is necessary to disable the auxiliary heat, except

for defrost, until the outdoor ambient is less than the structure’s

balance point. This is accomplished by using the low-voltage

wiring as shown in Fig. 36. Wire the 24vac W2 signal from the

indoor thermostat to W3 of the control, and W2 of the control to

W2 of the indoor unit. When the outdoor ambient is less than the

setting of the balance-point POT, the 24vac signal energizes the

auxiliary heat (W2) of the indoor unit.

IV. MAJOR COMPONENTS

TWO-SPEED CONTROL

The 2-speed control board controls the following functions:

•

High- and low-compressor contactor operation

Outdoor fan-motor operation

Crankcase-heater operation

Compressor protection

EMERGENCY HEAT

If the 2-speed control receives a call for auxiliary heat (W2)

without a heat-pump heating (Y1) call, the second auxiliary stage

(W3) is energized. This ensures all available heat is energized if

the indoor thermostat is switched to emergency heat.

Pressure-switch monitoring

Second-stage latching

COMPRESSOR PTC-OVERLOAD PROTECTION

Time delays

The control senses the resistance of the compressor internal

positive-temperature coefficient (PTC) overloads. If the resistance

of the PTCs is out of range, the control shuts off the unit until the

resistance range is acceptable. See Table 16 for compressor PTC

ranges.

5-minute time-delay speedup (bypass)

Heat pumps:

•

Time/temperature defrost

Defrost-interval selection

Furnace interface

TABLE 16—COMPRESSOR PTC RANGES

Electric-heat staging

COMPRESSOR INTERNAL-PTC RESISTANCE

HEADER-PIN HOUSING

Safe Range (77°F)

To trip

1.5k to 7.8k ohms

26k to 34k ohms

8.4k to 10k ohms

The header-pin housing is the plastic assembly which holds the

stripped-lead ends for field connections. The 2-speed control

receives the 24vac low-voltage control-system inputs through the

housing/pins. The housing also contains jumpers which the control

uses for system configuration, such as heat pump versus air

conditioner. See Fig. 37 for header-pin housing configurations.

To reset

When the control turns off the outdoor unit due to out-of-range

PTCs, the unit remains off for 15 minutes with the outdoor fan

running. After 15 minutes, the control checks the resistance every

5 minutes until it reaches the reset range. During this time, a

malfunction signal appears on the control board. If this happens,

remove the wires on control board at S1 and S2 and measure the

resistance across the leads. When the resistance reaches 8,400 to

10,000 ohms, system operation may be resumed. If the resistance

remains outside this range, a quick check of the leads at the

compressor should be made. Loose connections can cause inaccu-

rate readings. If a PTC trip occurs 3 times, the control will lock out

the outdoor-unit operation and provide malfunction signals at both

the control and indoor thermostat.

TWO-SPEED COMPRESSOR

The 2-speed compressor contains motor windings that provide

low-speed, 4–pole (1750 rpm) and high-speed, 2–pole (3500 rpm)

operation. Refer to Fig. 38 to determine which windings are

energized at each speed. Refer to Compressor Winding-Check

section under Troubleshooting and Table 18 for appropriate

winding resistances.

The 2-speed compressor is also protected by an internal-pressure

relief (IPR), which relieves discharge gas into the compressor shell

(low side) when the differential between suction and discharge

TABLE 17—FACTORY DEFAULTS

FUNCTION

FAILED COMPONENT

DEFAULT

Crankcase Heater

Energized during any off cycle

Does not function

Second-Stage Latching

Balance point does not function, but

interface still energizes furnace and

locks out heat pump with a call for W2

Furnace Interface

Ambient Thermistor

Unit only runs in high-

compressor speed

Heating Switchover Speed Point

Defrost Initiation

Defrost is initiated based on coil

temperature only

Outdoor Thermostat for

Auxiliary Heat

Anytime there is a call for W2,

W3 is also energized.

Defrost occurs at each time interval,

but terminates after 5 minutes

Outdoor Coil Thermistor

Furnace Interface Jumper

Defrost Initiation and Termination

Furnace Interface

Does not function

—33—

pressures exceeds 500 psi. The compressor is also protected by 3

PTC devices attached to the motor windings. The PTC’s resistance

is sensed by the 2-speed control board. See Table 16 for resistance

ranges.

C - TRANSFORMER COMMON

R - TRANSFORMER LINE

MECHANICALLY INTERLOCKED CONTACTORS

The 2-speed products are equipped with mechanically interlocked

contactors. Each contactor has interconnecting linkage, providing

independent interlocks.

The 2-speed control provides the electrical interlock. The contac-

tors are supplied with 240v coils, which reduce the va require-

ments of the low-voltage (24vac) control system.

W2 - FIRST STAGE AUXILIARY HEAT

O - REVERSING VALVE

Y2 - SECOND STAGE COOLING/HEAT PUMP

Y1 - FIRST STAGE COOLING/HEAT PUMP

W3 - SECOND STAGE AUXILIARY HEAT

L - MALFUNCTION LIGHT

TEMPERATURE THERMISTORS

Thermistors are electronic devices which sense temperature. As

the temperature increases, the resistance decreases. Two ther-

mistors are used to sense temperature: one senses outdoor ambient,

and the other senses coil temperature (heat pump only). Refer to

Fig. 39 for resistance values versus temperature.

If the outdoor ambient thermistor should fail, a malfunction signal

appears on the indoor thermostat and 2-speed control. The control

does not initiate second-stage latching, crankcase heater is turned

on during all off-cycles, heating defaults to high speed, and defrost

initiates on demand from coil thermistor. (See Table 17.)

4 - TON

IF NO JUMPER IS

INSTALLED, DEFAULT

IS 3 - TON

5 - TON

JUMPER FOR

HEAT PUMP ONLY

A93576

THERMISTOR CURVE

Fig. 37—Header-Pin Housing

T3 T8

T7 T2

EXTERNAL MAIN

100

120

MAIN WINDING

4 POLE START

2 POLE START

TEMPERATURE (DEG. F)

A91431

Fig. 39—Resistance Values Versus Temperature

If the outdoor coil thermistor should fail, a malfunction signal

appears on the indoor thermostat and 2-speed control. The control

defrosts every 90 minutes of heating operation and terminates in 5

minutes. (See Table 17.)

V. LED FUNCTION/MALFUNCTION LIGHTS

HIGH SPEED

(L1) T1 + T7

(L2) T2 + T3

LOW SPEED

(L1) T1

(L2) T7 + T8

The 2-speed control is equipped with an LED function/ malfunc-

tion light.

NOTE: Only malfunction signal appears at thermostat. Both

function and malfunction signals appear at control board. (See Fig.

33 for LED location.) Table 15 provides the function/malfunction

code, location, and definition.

A92015

Fig. 38—Energizing Windings

VI. TROUBLESHOOTING

NOTE: Troubleshooting charts for air conditioning and heat

pump units are provided in the back of this manual — see Fig. 52,

53, and 54.

TABLE 18—TWO-SPEED COMPRESSOR

(WINDING RESISTANCE AT 70°F ± 2°)

WINDING

T1-T2

3 TON

0.80

4 TON

0.70

5 TON

COMPRESSOR WINDING CHECK

0.60

1.80

1.00

2.00

The 2-speed compressor is nothing more than 2 single-phase

motors within 1 compressor shell. When the compressor fails to

start or run, there are 3 tests that can be made: open, ground, or

short. This compressor has no internal line-break overload; how-

ever, it does have PTC motor protectors. See Compressor PTC-

Overload Protection section for PTC overload information.

T1-T3

3.20

2.20

T1-T7

1.30

1.00

T1-T8

3.10

2.20

—34—

NOTE: To ensure accurate ohm measurements, place ohmmeter

probes on flat surface of compressor-terminal tabs, not the brass

mounting screw.

24v power. If the fault clears, check to ensure the indoor and

outdoor unit and electrical service are properly grounded. If the

entire system is grounded, the control board should be replaced, as

the control is not field reparable. If the control-board light is

flashing, see LED and Table 15 for function/malfunction defini-

tion. Cycling 24 vac to control board resets previous error

messages and any lockouts which have occurred. See Table 19 for

more information regarding control-board operation.

Open

To determine if a winding has an actual break in the internal wires

and current is unable to pass through:

1. Be sure all power is off.

CONTROL-BOARD POWER INPUTS AND OUTPUTS

See Fig. 33 and 37 for inputs and outputs.

BLEED RESISTOR

2. Discharge all capacitors.

3. Remove wires from terminals T1, T2, T3, T7, and T8.

4. Use an ohmmeter on 0-1000 ohm scale to check resistance.

(See Fig. 38, 40, and 41 and Table 18.)

The bleed resistor is a 150k, 2–watt resistor across the compressor-

run capacitor to protect service technician from injury by electrical

shock. Capacitor will bleed-off approximately 1 minute after

power to outdoor unit is turned off. If run capacitor is changed out,

be sure to place bleed resistor on new capacitor. If bleed resistor is

damaged, replace resistor.

Because winding resistances are usually less than 10 ohm, each

reading will appear to be approximately zero ohm. If during any

check the resistance remains at 1000 ohm, an open or break exists,

and the motor or compressor should be replaced.

Ground

START CAPACITOR AND RELAY

To determine if any wire has broken and come in direct contact

with the housing or shell, causing a direct short to ground:

The 2-speed system has a second start relay in the control box. One

start relay is for low-speed start, and the second is for high-speed

start. Both start relays use a common-start capacitor. When

servicing this equipment, be certain system starts in both low- and

high-speed operation.

1. Be sure all power is off.

2. Discharge all capacitors.

3. Remove wires from T1, T2, T3, T7, and T8.

REFRIGERATION SYSTEM

I. REFRIGERATION CYCLE

4. Allow crankcase heater to remain on for several hrs before

checking motor to ensure that windings are not saturated

with refrigerant.

In a refrigeration system, refrigerant moves heat from one place to

another. It is useful to understand flow of refrigerant in a system.

5. Using an ohmmeter on R X 10,000 ohm scale, place 1 meter

probe on ″ground″ motor or compressor frame. Make a

good metal-to-metal contact. Place other probe on terminals

T1, T2, T3, T7, and T8 in sequence. Note meter scale.

In a straight cooling system, compressed hot gas leaves compres-

sor and enters condensing coil. As gas passes through condenser

coil, it rejects heat and condenses into liquid. The liquid leaves

condensing unit through liquid line and enters metering device at

indoor coil. As it passes through metering device, it becomes a

gas-liquid mixture. As it passes through indoor coil, it absorbs heat

and refrigerant and is again compressed to a hot gas. The cycle

then repeats.

If any reading of zero or low resistance is obtained, the motor is

grounding. Replace the compressor.

Short

NOTE: This is an extremely critical test and is not advised unless

the following conditions are met.

In a heat pump, the basic cycle is the same. (See Fig. 42.)

Reversing valve in system decides which coil, indoor or outdoor,

becomes evaporator or condenser. It rejects heat into the home

after heat is absorbed by outdoor evaporator coil, thus the home is

heated.

The correct motor-winding resistances must be known before

testing. See Table 18 for cold-motor winding resistance.

The temperature of the windings must be specified, 70°F ± 2°F.

The resistance-measuring instrument must have an accurate ohm-

meter (such as a Wheatstone bridge or null balance-type instru-

ment).

In cooling cycle, the indoor coil becomes the evaporator. It absorbs

heat from the home and rejects it through the outdoor condenser

coil, thus the home is cooled.

The motor must be dry or free from direct contact with liquid

refrigerant.

A unique feature of the heat pump is that metering devices are

designed to meter refrigerant in one direction of flow and allow

refrigerant to pass unhindered in the other direction. If indoor-

metering device is metering refrigerant, the outdoor device by-

passes refrigerant and vice versa. This allows both coils to serve a

dual function.

To determine if any wires have broken through their insulation and

come in direct contact with each other, thereby ″shorting″ all or

part of the winding(s):

1. Be sure all power is off.

2. Discharge all capacitors.

II. LEAK DETECTION

3. Remove wires from terminals T1, T2, T3, T7, and T8.

CAUTION: Always wear safety glasses and gloves

4. Subtract instrument probe and lead resistance from each

reading. If any reading is within ± 20 percent of the known

resistance from Table 18, the motor probably does not have

a short. Usually a considerable difference will be noted if a

turn-to-turn short is present.

when handling refrigerants.

New installations should be checked for leaks prior to complete

charging.

CONTROL BOARD FAILURE

If a system has lost all or most of its charge, system must be

pressurized again, up to approximately 150 lb minimum. This can

be done by adding refrigerant using normal charging procedures,

or it may be pressurized with nitrogen (less expensive than

refrigerant). Nitrogen also leaks faster than R-22 and is not

absorbed by refrigeration oil. Nitrogen cannot, however, be

detected by a leak detector. (See Fig. 43.)

The control board continuously monitors its own operation and the

operation of the system. The diagnostic feature allows easy

troubleshooting of the control and system in the field. If a failure

occurs, the LED light on the control will flash a failure code. If the

failure is internal to the control board, the light will stay on

continuously (no flash). Before replacing control board, reset the

—35—

SCHEMATIC DIAGRAM

(LADDER FORM)

COMP

MAIN

EXT

LOW

START

HIGH

MAIN

START

EQUIP

GND

CAP

A91446

Fig. 40—Low-Speed Windings

SCHEMATIC DIAGRAM

(LADDER FORM)

COMP

MAIN

EXT

MAIN

LOW

START

HIGH

START

EQUIP

GND

CAP

A91445

Fig. 41—High-Speed Windings

—36—

In all instances, when a leak is found, system charge must be bled

down and leak repaired before final charging and operation. After

leak testing or leak is repaired, evacuate system, and recharge with

correct refrigerant charge.

COOLING CYCLE

REVERSING VALVE

(ENERGIZED)

OUTDOOR FAN

INDOOR

FAN

INDOOR COIL

ACCUMULATOR

SUCTION SERVICE

PORT AT SERVICE

VALVE (CLG CYCLE)

COMP

STRAINER

OUTDOOR

COIL

STRAINER

SUCTION

SERVICE

PORT

LIQUID LINE

PRESSURE SWITCH

(METERING)

(BYPASSING)

HEAT PUMP

ACCESSORY

FILTER DRIER

(DUAL FLOW)

LIQUID LINE SERVICE PORT

AT SERVICE VALVE (CLG CYCLE)

A88400

Fig. 42—Heat Pump Refrigerant-Flow Diagrams

CAUTION: Due to the high pressure of nitrogen, it

should never be used without a pressure regulator on the

tank.

Leaks in a system pressurized with refrigerant can be spotted with

a leak detector that detects extremely small refrigerant leaks. This

discussion assumes that system is pressurized with either all

refrigerant or a mixture of nitrogen and refrigerant.

If system has been operating for some time, make first check for

a leak visually. Since refrigerant carries a small quantity of oil,

traces of oil at any joint or connection are an indication that

refrigerant is leaking at that point.

A simple and inexpensive method of testing for leaks is to use soap

bubbles. Any solution of water and soap may be used. Soap

solution is applied to all joints and connections in system. A small

pinhole leak is located by tracing bubbles in soap solution around

leak.

Use electronic leak detector to check for leaks. This unquestion-

ably is the most efficient and easiest method for checking leaks.

There are various types of electronic leak detectors. Generally

speaking, they are all portable, and most are lightweight, consist-

ing of a box with several switches and a probe or sniffer. Detector

is turned on and probe is passed around all fittings and connections

in system. Leak is detected by either a movement of a pointer on

detector dial, by a buzzing sound, or a light.

A88401

Fig. 43—Leak Detector

III. BRAZING

When brazing is required in the refrigeration system, certain basics

should be followed:

1. Clean joints make the best joints. To clean:

a. Remove all oxidation from surfaces to a shiny finish

before brazing.

TABLE 19—24V PIN CONNECTION TROUBLESHOOTING

MODE OF OPERATION

18-PIN CONNECTOR

TERMINAL

DESIGNATION

LOCATION ON

CONTROL BOARD

VOLTAGE

PATH

VOLTAGE

REQUIRED

POSSIBLE SOURCE

OF PROBLEM

All

R-C

Y1,0-C

Y1, Y2, 0-C

Y1-C

2-1

8,6-1

8,7,6-1

8-1

Input

Check transformer (secondary)

Check thermostat

Low-speed Cooling

High-speed Cooling

Low-speed Heating

Check thermostat

Y1-C

8-1

Check thermostat

High-speed Heating

Defrost

Outdoor temperature below

speed; change temperature

Y2-C

Y1-C

7-1

8-1

Output

Input

Check thermostat

Outdoor temperature below 50°F;

Coil temperature less than 30°F

Y2, W2, 0-C

7,5,6-1

Output

Y1, W2-C

W3, Y2-C

7,5-1

9,8-1

Input

Check thermostat

Second Stage of

Auxiliary Heat

Output

Check balance-point setting

Cooling Second-

stage Latching

Ambient thermistor failure;

Check second-stage POT

Y1, Y2, 0-C

8,7,6-1

Input

—37—

SERVICE PORT

W/SCHRADER

CORE

STEM

FIELD

SIDE

STEM

SERVICE PORT

W/SCHRADER CORE

FIELD

SIDE

SEAT

BAR STOCK FRONT SEATING VALVE

FORGED FRONT SEATING VALVE

A91447

A91448

Fig. 44—Service Valves

b. Remove all flux residue with brush and water while

material is still hot.

pressurized. To pressurize the service port, this valve must be

moved off the back-seating position. This valve does not contain a

Schrader fitting. Both types of service valves are designed for

sweat connection to the field tubing.

2. Use ″sil-fos″ or ″phos-copper″ for copper-to-copper only.

No flux is required.

The service valves in the outdoor unit come from the factory

front-seated. This means that the refrigerant charge is isolated from

the line-set connection ports. Some heat pumps are shipped with

sweat-adapter tube. This tube must be installed on the liquid-

service valve. After connecting the sweat adapter to the liquid-

service valve of a heat pump, the valves are ready for brazing. The

interconnecting tubing (line set) can be brazed to the service valves

using either silver-bearing or non-silver-bearing brazing material.

Consult local codes.

Before brazing the line set to the valves, the belled ends of the

sweat connections on the service valves must be cleaned so that no

brass plating remains on either the inside or outside of the bell

joint. To prevent damage to the valve and/or cap ″O″ ring, use a

wet cloth or other acceptable heat-sinking material on the valve

before brazing. To prevent damage to the unit, use a metal barrier

between brazing area and unit.

3. Silver solder is used on copper-to-brass, copper-to-steel, or

copper-to-copper. Flux is required when using silver solder.

4. Fluxes should be used carefully. Avoid excessive applica-

tion and do not allow fluxes to enter into the system.

5. Proper brazing temperature of copper is when it is heated to

a dull red color.

This section on brazing is not intended to teach a technician how

to braze. There are books and classes that teach and refine brazing

techniques. The basic points above are listed only as a reminder.

IV. SERVICE VALVES

WARNING: Never attempt to make repairs to existing

service valves. Unit operates under high pressure. Dam-

aged seats and o-rings should not be replaced. Replace-

ment of entire service valve is required. Tampering with

damaged valves can cause personal injury or death.

Service valve must be replaced by properly trained

service technician.

After the brazing operation and the refrigerant tubing and evapo-

rator coil have been evacuated, the valve stem can be turned

counterclockwise until it opens or back-seats, which releases

refrigerant into tubing and evaporator coil. The system can now be

operated.

Back-seating service valves must be back-seated (turned counter-

clockwise until seated) before the service-port caps can be re-

moved and hoses of gage manifold connected. In this position,

refrigerant has access from and through outdoor and indoor unit.

The service valve-stem cap is tightened to 20 ± 2 ft/lb torque and

the service-port caps to 9 ± 2 ft/lb torque. The seating surface of

the valve stem has a knife-set edge against which the caps are

tightened to attain a metal-to-metal seal. If accessory pressure

switches are used, the service valve must be cracked. Then, the

knife-set stem cap becomes the primary seal.

Service valves provide a means for holding original factory charge

in outdoor unit prior to hookup to indoor coil. They also contain

gage ports for measuring system pressures and provide shutoff

convenience for certain types of repairs. (See Fig. 44.)

Two types of service valves are used in outdoor residential

equipment. The first type is a front-seating valve, which has a

service port that contains a Schrader fitting. The service port is

always pressurized after the valve is moved off the front-seat

position.

The service valve cannot be field-repaired; therefore, only a

complete valve or valve stem and service-port caps are available

for replacement.

The second type is a combination front-seating/back-seating valve,

which has a metal-to-metal seat in both the open and closed

positions. When it is fully back-seated, the service port is not

—38—

PISTON BODY

FEEDER

TUBES

PISTON

(ORIENT AS SHOWN)

STRAINER

BRASS

HEX NUT

PISTON

PISTON RETAINER

FLARE ADAPTER

INTERNAL STRAINER

TEFLON

SEAL

PISTON

RETAINER

BRASS

HEX

BODY

PRODUCTION

EXCEPT 1992

A91138

A94004

Fig. 45—Check-Flo-Rater™ Components

If the service valve is to be replaced, a metal barrier must be

inserted between the valve and the unit to prevent damaging the

unit exterior from the heat of the brazing operations.

5. Slide piston out by inserting a small, soft wire with small

kinks through metering hole. Do not damage metering hole,

sealing surface around piston cones, or fluted portion of

piston.

CAUTION: Wear safety glasses and gloves when han-

dling refrigerants.

6. Clean piston refrigerant-metering hole.

7. Install a new retainer O-ring or retainer assembly before

reassembling bypass-type Check-Flo-Rater™.

RELIANT AND CUBE PRODUCTS PRODUCED IN 1992

Pumpdown Procedure

1. Shut off power to unit.

Service valves provide a convenient shutoff valve useful for

certain refrigeration-system repairs. System may be pumped down

to make repairs on low side without losing complete refrigerant

charge.

2. Reclaim outdoor-unit refrigerant.

3. Loosen brass hex nut and remove line from brass hex body.

4. Slide piston out by inserting a small, soft wire with small

kinks through metering hole. Do not damage metering hole,

sealing surface around piston cones, or fluted portion of

piston.

1. Attach pressure gage to suction service-valve gage port.

2. Front seat liquid-line valve.

5. Clean piston refrigerant-metering hole.

6. Always replace Teflon seal with new seal. Never try to

reuse old seals.

3. Start unit in cooling mode. Run until suction pressure

reaches 5 psig (35kPa). Do not allow compressor to pump

to a vacuum.

7. Reassemble brass nut and brass hex body. Be sure orienta-

tion is as shown in Fig. 45.

4. Shut unit off. Front seat suction valve.

NOTE: All outdoor unit coils will hold only factory-supplied

amount of refrigerant. Excess refrigerant, such as in long-line

applications, may cause unit to relieve pressure through internal

pressure-relief valve (indicated by sudden rise of suction pressure)

before suction pressure reaches 5 psig (35kPa). If this occurs, shut

off unit immediately, front seat suction valve, and recover remain-

ing pressure.

VI. REVERSING VALVE

In heat pumps, changeover between heating and cooling modes is

accomplished with a valve that reverses flow of refrigerant in

system. (See Fig. 46.) This reversing-valve device is easy to

troubleshoot and replace. The reversing-valve solenoid can be

checked with power off with an ohmmeter. Check for continuity

and shorting to ground. With control-circuit (24v) power on, check

for correct voltage at solenoid coil. Check for overheated solenoid.

With unit operating, other items can be checked, such as frost or

condensate water on refrigerant lines.

The sound made by a reversing valve as it begins or ends defrost

is a ″whooshing″ sound, as the valve reverses and pressures in

system equalize. An experienced service technician detects this

sound and uses it as a valuable troubleshooting tool.

Using a remote measuring device, check inlet and outlet line

temperatures. DO NOT touch lines. If reversing valve is operating

normally, inlet and outlet temperatures on appropriate lines should

be close. Any difference would be due to heat loss or gain across

valve body. Temperatures are best checked with a remote-reading,

electronic-type thermometer with multiple probes. Route thermo-

couple leads to inside of coil area through service-valve mounting-

plate area underneath coil. Fig. 47 and 48 show test points (TP) on

reversing valve for recording temperatures. Insulate points for