Allied Air Enterprises 4AC18LT User Manual

INSTALLATION AND MAINTENANCE INSTRUCTIONS  
4AC18LT SERIES  
Split System Air Conditioner  
Save these instructions for future reference  
WARNING  
The equipment covered in this manual is to be installed by trained and experienced service  
and installation technicians. Improper installation, modification, service, or use can cause  
electrical shock, fire, explosion, or other conditions which may cause personal injury, death,  
or property damage. Use appropriate safety gear including safety glasses and gloves when  
installing this equipment.  
WARNING  
TABLE OF CONTENTS  
Risk of electrical shock. Disconnect all remote power  
supplies before installing or servicing any portion of the  
system. Failure to disconnect power supplies can result  
INSTALLATION ....................................................2  
in property damage, personal injury, or death.  
START-UP ..........................................................13  
OPERATION ......................................................17  
MAINTENANCE .................................................21  
CONNECTION DIAGRAM..................................23  
WARNING  
Installation and servicing of air conditioning equipment  
can be hazardous due to internal refrigerant pressure  
and live electrical components. Only trained and  
qualified service personnel should install or service this  
equipment. Installation and service performed by  
unqualified persons can result in property damage,  
personal injury, or death.  
Manufactured By  
Allied Air Enterprises, Inc.  
A Lennox International Inc. Company  
215 Metropolitan Drive  
West Columbia, SC 29170  
WARNING  
Sharp metal edges can cause injury. When installing  
the unit, use care to avoid sharp edges.  
*506469-01*  
506469-01  
Issue 1008  
Page 1 of 24  
Install the unit high enough above the ground or roof to  
allow adequate drainage of defrost water and prevent  
ice buildup.  
If unit coil cannot be mounted away from prevailing winter  
winds, a wind barrier should be constructed (See Figure 3).  
Size the barrier at least the same height and width as the  
outdoor unit. Mount barrier 24” from the sides of the unit in  
the direction of the prevailing winds.  
In heavy snow areas, do not locate the unit where drifting  
snow will occur. The unit base should be elevated above  
the depth of average snows.  
NOTE: Elevation of the unit may be accomplished by  
construction a frame using suitable materials. If a  
support frame is constructed, it must not block drain  
holes in unit base.  
When installed in areas where low ambient temperatures  
exist, locate unit so winter prevailing winds do not blow  
directly into outdoor coil.  
Locate unit away from overhanging roof lines which  
would allow water or ice to drop on, or in front of, coil or  
into unit.  
Slab Mounting  
Figure 3  
When installing a unit at grade level, install on slab high  
enough above grade so that water from higher ground will  
not collect around the unit (See Figure 2). Slab should have  
a slope tolerance away from the building of 2° or 2” per 5’.  
This will prevent ice from building up under the unit during a  
defrost cycle. Refer to following roof mounting section for  
barrier construction if unit must face prevailing winter winds.  
Electrical Wiring  
All field wiring must be done in accordance with the National  
Electrical Code (NEC) recommendations, Canadian  
Electrical Code (CEC) and CSA Standards, or local codes,  
where applicable.  
Slab Mounting  
Refer to the furnace or blower coil installation instructions  
for additional wiring application diagrams and refer to unit  
rating plate for minimum circuit ampacity and maximum  
overcurrent protection size.  
Discharge Air  
Building  
Structure  
WARNING  
Unit must be grounded in accordance with national and  
local codes. Failure to ground unit properly can result in  
personal injury or death.  
Mounting Slab  
Ground Level  
WARNING  
Figure 2  
Line voltage is present at all components when unit is  
not in operation on units with single pole contactors.  
Disconnect all remote electric power supplies before  
opening access panel. Unit may have multiple power  
supplies. Failure to disconnect all power supplies could  
result in personal injury or death.  
Roof Mounting  
Install unit at a minimum of 6” above surface of the roof to  
avoid ice buildup around the unit. Locate the unit above a  
load bearing wall or area of the roof that can adequately  
support the unit. Consult local codes for rooftop applications.  
506469-01  
Issue 1008  
Page 3 of 24  
Placement  
Brazing Connection Procedure  
Be aware that some localities are adopting sound ordinances  
based on how noisy the unit is at the neighbor’s home, not  
at the original installation. Install the unit as far as possible  
from the property line. When possible, do not install the unit  
directly outside a bedroom window. Glass has a verry high  
level of sound transmission. Figure 5 on page 5 shows how  
to place the outdoor unit and line set to reduce line set  
vibration.  
1. Cut ends of refrigerant lines square (free from nicks or  
dents). Debur the ends. The pipe must remain round; do  
not pinch end of line.  
2. Before making line set connections, use dry nitrogen to  
purge the refrigerant piping. This will help to prevent  
oxidation and the introduction of moisture into the system.  
3. Use silver alloy brazing rods (5% or 6% silver alloy for  
copper-to-copper brazing or 45% silver alloy for copper-to-  
brass or copper-to-steel brazing) which are rated for use  
with R410A refrigerant.  
Line Set Isolation  
Illustrations on the pages 6 and 7 demonstrate procedures  
which ensure proper refrigerant line set isolation. Figure 6  
shows how to install line sets on horizontal runs. Figure 7  
shows how to make a transition from horizontal to vertical.  
Figure 9 shows how to install line sets on vertical runs.  
4. Remove the Schrader core assemblies before brazing to  
protect them from damage due to extreme heat. Replace  
the cores when brazing is complete.  
Refrigerant Line Set Diameters (in.)  
5. Remove light maroon washers from service valves and  
shield light maroon stickers to protect them during brazing.  
Wrap a wet cloth around the valve body and copper tube  
stub to protect it from heat damage.  
Liquid Line  
Line S et Length and S ize  
B T UH  
12 f t. 25 ft. 50 ft. 75 ft. 100 ft.  
Outside Unit Placement & Installation  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
3/8  
1/2  
1/2  
3/8  
1/2  
1/2  
1/2  
24,000  
36,000  
48,000  
60,000  
Install unit away  
from windows  
S uction L ine  
L ine S et L ength a nd S ize  
12 f t . 25 ft. 50 ft. 75 ft. 10 0 f t .  
B T U H  
3/4  
3/4  
7/8  
3/4  
7/8  
3/4  
7/8  
24,000  
7/8  
36,000 7/8  
48,000 7/8  
1-1/8  
1-1/8  
1-1/8  
1-1/8  
1-1/8  
Two 90° elbows installed in lineset  
will reduce lineset vibration  
1-1/8 1-1/8  
60,000  
1-1/8 1-1/8  
1-1/8  
Figure 5  
For installations exceeding 50’, contact  
Technical Services.  
Table 2  
506469-01  
Issue 1008  
Page 5 of 24  
Refrigerant Piping  
Thermostat Designations  
If the 4AC18LT unit is being installed with a new indoor coil  
and line set, the refrigerant connections should be made as  
outlined in this section. If an existing line set and/or indoor  
coil will be used to complete the system, refer to this section  
as well as the section that follows entitled - Flushing  
Existing Line Set and Indoor Coil.  
If this unit is being matched with an approved line set or  
indoor coil which was previously charged with R-22  
refrigerant, the line set and coil must be flushed prior to  
installation. If the unit is being used with and existing indoor  
coil which was equipped with a liquid line which served as a  
metering device (RFCI), the liquid line must be replaced prior  
to the installation of the 4AC18LT unit.  
See unit wiring diagram for power supply connections.  
If the indoor unit is not equipped with a blower relay, one must  
be field supplied and installed.  
Field refrigerant piping consists of liquid and suction lines  
from the outdoor unit (sweat connections) to the indoor coil  
(flare or sweat connections).  
Do not connect C (common) connection between indoor unit  
and thermostat except when required by the indoor thermostat.  
Refer to thermostat installation instructions. C (common)  
connection between indoor unit and outdoor unit required for  
proper operation.  
Select line set diameters from Table 2 to ensure that oil  
returns to the compressor. Size vertical suction riser to  
maintain minimum velocity at minimum capacity.  
Recommended line length is 50’ or less. If more than 50’  
line set is required, contact Technical Services. Table 2  
shows the diameters for line sets up to 100’ although vertical  
lift applications and trapping requirements need to be  
reviewed with Technical Services for line sets over 50’.  
Figure 4  
1. Install line voltage power supply to unit from a properly  
sized disconnect switch. Any excess high voltage field wiring  
should be trimmed or secured away from the low voltage  
field wiring.  
Installing Refrigerant Line  
During the installation of an air conditioning system, it is  
important to properly isolate the refrigerant line to prevent  
unnecessary vibration. Line set contact with the structure  
(wall, ceiling, or floor) may cause objectionable noise when  
vibration is translated into sound. As a result, more energy  
or vibration can be expected. Close attention to line set  
isolation must be observed.  
2. Ground unit at unit disconnect switch or to an earth ground.  
To facilitate conduit, a hole is in the bottom of the control  
box. Connect conduit to the control box using a proper  
conduit fitting. Units are approved for use only with copper  
conductors. 24V Class II circuit connections are made in  
the low voltage junction box. Refer to Figure 4 for high  
voltage field wiring diagram. Acomplete unit wiring diagram  
is located inside the unit control box cover.  
Following are some points to consider when placing and  
installing a high-efficiency outdoor unit:  
3. Install room thermostat on an inside wall that is not subject  
to drafts, direct sunshine, or other heat sources.  
4. Install low voltage wiring from outdoor to indoor unit and  
from thermostat to indoor unit (See Figure 5).  
5. Do not bundle any excess 24V control wire inside control  
box. Run control wire through installed wire tie and tighten  
wire tie to provide low voltage strain relief and to maintain  
seperation of field-installed low and high voltage circuits.  
506469-01  
Issue 1008  
Page 4 of 24  
6. Braze the line set to the service valve. Quench the joints  
with water or a wet cloth to prevent heat damage to the  
valve core and opening port. The tube end must stay  
bottomed in the fitting during final assembly to ensure  
proper seating, sealing, and rigidity.  
CAUTION  
When flushing existing line set and/or indoor coil, be sure to  
empty all existing traps. Residual mineral oil can act as an  
insulator, preventing proper heat transfer. It can also clog  
the thermal expansion valve, reducing system performance  
and capacity. Failure to properly flush system as explained  
in these instructions will void warranty.  
7. Install the thermal expansion valve which is sold  
separately and which is approved for use with R410A  
refrigerant in the liquid line at the indoor coil (see Refrigerant  
Metering Device on page 9).  
Refrigerant Line Sets: Installing Horizontal Runs  
To hang line set from joist or rafter,  
use either metal strapping material  
or anchored heavy nylon wire ties.  
Wire Tie  
(around vapor line only)  
8  
Strapping Material  
(around vapor line only)  
Floor Joist or  
Roof Rafter  
Tape or Wire Tie  
8’  
Strap the vapor line to the joist or rafter  
at 8intervals then strap the liquid line  
to the vapor line.  
Metal Sleeve  
Floor Joist or Roof Rafter  
Tape or Wire Tie  
Figure 6  
506469-01  
Issue 1008  
Page 6 of 24  
Refrigerant Line Sets: Transition from Vertical to Horizontal  
Automotive  
Muffler-Type  
Hanger  
Anchored  
Heavy Nylon  
Wire Tie  
Strap Liquid  
Line to Vapor  
Line  
Strap Liquid  
Line to Vapor  
Line  
Wall  
Stud  
Wall  
Stud  
Liquid Line  
Liquid Line  
Vapor Line Wrapped  
Vapor Line Wrapped  
Metal Sleeve  
in Armaflex  
Metal Sleeve  
in Armaflex  
Figure 7  
Refrigeraant Line Sets: Installing Vertical Runs (new construction shown)  
IMPORTANT: Refrigerant  
lines must not contact wall.  
NOTE: Similar installation practices  
should be used if line set is to be  
installed on exterior of outside wall.  
Outside Wall  
Vapor Line  
Liquid Line  
Wood Block  
Between Studs  
Wire Tie  
Inside Wall  
Strap  
Sleeve  
Vapor Line Wrapped  
with Armaflex  
Wire Tie  
Liquid Line  
Outside Wall  
Wood Block  
IMPORTANT:  
Refrigerant  
lines must not  
contact structure.  
Wire Tie  
Strap  
Caulk  
Fiberglass  
PVC Pipe  
Insulation  
Sleeve  
Figure 8  
506469-01  
Issue 1008  
Page 7 of 24  
Flushing Existing Line Set and Indoor Coil  
This procedure should not be performed on systems  
which contain contaminants, such as compressor burn  
out.  
If the existing outdoor unit is equipped with manual shutoff  
valves AND new R-22 refrigerant will be used to flush the  
system:  
Start the existing R-22 refrigerant system in cooling mode  
and close the liquid line valve. Pump all the existing R-22  
refrigerant back into the outdoor unit.  
Required Euipment  
The following equipment is needed to flush the existing line  
set and indoor coil (See Figure 9). Two clean R-22 recovery  
bottles, an oil-less recovery machine with a “pump down”  
feature, and two sets of gauges (one for use with R-22 and  
one for use with R410A).  
(It may be necessary to bypass the low pressure switches  
to ensure complete refrigerant evacuation.)  
When the low side system pressures reach 0 psig, close  
the suction line valve. Disconnect all power to the existing  
outdoor unit. Refer to the gauges after shutdown to confirm  
that the valves are not allowing refrigerant to flow back into  
the low side of the system. Disconnect the liquid and suction  
lines from the existing outdoor unit.  
Flushing Procedure  
IMPORTANT: The line set and/or indoor coil must be  
flushed with at least the same amount of refrigerant that  
previously charged the system. Check the charge in the  
flushing cylinder before flushing the unit.  
1. Remove existing R-22 refrigerant using the appropriate  
procedure.  
2. Remove the existing outdoor unit. Set the new R410A  
unit and follow the brazing connection procedure outlined  
previously on this page to make line set connections. Do  
not install the R410A thermal expansion valve at this  
time.  
If the existing outdoor unit is not equipped with shutoff valves,  
or if the unit is not operational AND the existing R-22  
refrigerant will be used to flush the system:  
3. Make low voltage and line voltage connections to the  
new outdoor unit. Do not turn on power to the unit or  
open the outdoor unit service valves at this time.  
Disconnect all power to the existing outdoor unit. Connect  
the existing unit, a clean recovery cylinder, and the recovery  
machine according to the instructions provided with the  
recovery machine. Remove all R-22 refrigerant from the  
existing system. Refer to the gauges after shutdown to  
confirm that the entire system is completely void of  
refrigerant. Disconnect the liquid and suction lines from the  
existing outdoor unit.  
Flushing Connections  
Figure 9  
506469-01  
Issue 1008  
Page 8 of 24  
4. Remover the existing R-22 refrigerant flow control orifice  
or thermal expansion valve before continuing with flushing  
procedures. R-22 flow control devices are not approved for  
use with R410A refrigerant and may prevent proper flushing.  
Use a field-provided fitting to reconnect the lines.  
An R410A system will not operate properly with an R-22  
metering device.  
Install the refrigerant metering device as shown in Figure  
10. Do not twist cap tubes when loosening the seal nut  
from the orifice housing. Use wrench to back up the  
distributor.  
5. Remove the pressure tap valve cores from the 4AC18LT  
units service valves. Connect an R-22 cylinder with clean  
refrigerant to the suction service valve. Connect the R-22  
gauge set to the liquid line valve and connect a recovery  
maching with an empty recovery tank to the gauge set.  
6. Set the recovery machine for liquid recovery and start  
the recovery machine. Open the gauge set valves to allow  
the recovery machine to pull a vacuum on the existing system  
line set and indoor coil.  
7. Invert the cylinder of clean R-22 and open its valve to  
allow liquid refrigerant to flow in to the system through the  
suction line valve. Allow the refrigerant to pass from the  
cylinder and through the line set and the indoor coil before it  
enters the recovery machine.  
8. After all of the liquid refrigerant has been recovered, switch  
the recovery machine to vapor recovery so that all of the R-  
22 vapor is recovered. Allow the recovery machine to pull a  
vacuum on the sytem.  
Figure 10  
Expansion Valve Systems  
NOTE: Asingle system flush should remove all of the mineral  
oil from the existing refrigerant lines and indoor coil. Asecond  
flushing may be done (using clean refrigerant) if insufficient  
amounts of mineral oil were removed during the first flush.  
After each system flush, allow the recovery machine to  
pull a vacuum on the system at the end of the procedure.  
Expansion valves equipped with Chatleff-type fittings are  
available from the manufacturer. See Table 4 for proper  
TXV for each unit.  
TXV Data  
9. Close the valve on the inverted R-22 cylinder and the  
gauge set valves. Pump the remaining refrigerant out of  
the recovery machine and turn the machine off.  
MODEL  
PART NUMBER  
H4TXV01  
H4TXV03  
4AC18LT- 24, -36  
4AC18LT - 48, -60  
10. Use nitrogen to break the vacuum on the refrigerant  
lines and indoor coil before removing the recovery machine,  
gauges, and R-22 refrigerant drum. Re-install pressure tap  
valve cores into the 4AC18LT unit’s service valves.  
Table 4  
To install an expansion valve (See Figure 10 above):  
11. Install the fixed orifice (or thermal expansion valve  
approved for use with R410A refrigerant) in the liquid line at  
the indoor coil.  
1. Separate the distributor assembly and remove the piston  
orifice and used teflon seal. Insert nozzle end of the  
expansion valve along with a new teflon seal into the  
distributor and tighten to 20 - 30 ft. lbs. Use backup wrench  
on all wrench flats. Overtightening will crush the teflon  
seal and may cause a leak.  
Refrigerant Metering Device  
4AC18LT units are designed for use with TXV systems.  
Refer to the appropriate following section for information on  
installing the chosen refrigerant metering device.  
2. Attach liquid line portion of distributor assembly along  
with new teflon seal to the inlet of the expansion valve.  
Tighten to 20 - 30 ft. lbs. Use backup wrench on all wrench  
flats. Overtightening will crush the teflon seal and may  
cause a leak.  
506469-01  
Issue 1008  
Page 9 of 24  
3. Connect the external equalizer line to the equalizer port  
on the suction line and tighten to 8 ft.lbs.  
Suction Line (Ball Type) Service Valve  
Suction line (ball type) service valves function the same way  
as the other valves; the difference is in the construction (See  
Figure 12).  
4. Strap the superheat sensing bulb to the suction header.  
If installing an expansion valve on an indoor coil that  
previously used a fixed orifice, be sure to remove the existing  
fixed orifice. Failure to remove a fixed orifice when installing  
an expansion valve to the indoor coil will result in improper  
operation and damage to the system.  
The ball valve is equipped with a service port with a factory-  
installed Schrader valve. A service port cap protects the  
Schrader valve from contamination and serves as the  
primary seal.  
Leak Testing  
Manifold Gauge Set  
After the line set has been connected to the indoor and  
outdoor units, the line set connections and indoor unit must  
be checked for leaks.  
Manifold guage sets used with systems charged with R410A  
refrigerant must be capable of handling the higher system  
operating pressures. The gauges should be rated for use  
with pressures 1 - 800 on the high side and a low side of 30”  
vacuum to 250 psi with dampened speed to 500 psi. Gauge  
hoses must be rated for use at up to 800 psi of pressure  
with a 4000 psi burst rating.  
Liquid and Suction Line Service Valves  
The liquid line and suction line service valves (See Figure  
11) and service ports are used for leak teating, evacuation,  
charging, and checking charge.  
Each valve is equipped with a service port which has a  
factory-installed Schrader valve. Aservice port cap protects  
the Schrader valve from contamination and serves as the  
primary leak seal.  
To Access the Schrader Port:  
1. Remove the service port cap with an adjustable wrench.  
2. Connect gauge to the service port.  
3. When testing is completed, replace service port cap.  
Tighten finger tight, then an additional 1/6 turn.  
To Open Liquid or Suction Line Service Valve:  
Remove stem cap with an adjustable wrench.  
Use service wrench with a hex-head extension to back the  
stem out counterclockwise as far as it will go. Use a 3/16”  
hex head extension for liquid line service valves and a 5/  
16” extension for suction line service valves.  
Replace the stem cap. Tighten finger tight, then tighten an  
additional 1/6 turn.  
To Close Liquid or Suction Line Service Valve:  
1. Remove the stem cap with an adjustable wrench.  
Figure 11  
2. Use a service wrench with a hex-head extension to turn  
the stem clockwise to seat the valve. Tighten firmly.  
3. Replace the stem cap. Tighten finger tight, then tighten  
an additional 1/6 turn.  
506469-01  
Issue 1008  
Page 10 of 24  
3. Open the high pressure side of the manifold to allow  
R410A into the line set and indoor unit. Weigh in a trace  
amount of R410A. (A trace amount is a maximum of 2 oz.  
of refrigerant or 3 lbs. pressure.) Close the valve on the  
R410A cylinder and the valve on the high pressure side of  
the manifold gauge set. Disconnect the R410A cylinder.  
4. Connect a cylinder of nitrogen with a pressure regulating  
valve to the center port of the manifold gauge set. When  
using high pressure gas such as nitrogen for this  
purpose, be sure to use a regulator that can control the  
pressure down to 1 or 2 psig.  
5. Adjust nitrogen pressure to 150 psig. Open the valve on  
the high side of the manifold gauge set to pressurize the  
line set and the indoor coil.  
6. After a short period of time, open a refrigerant port to  
make sure that an adequate amount of refrigerant has been  
added for detection (refrigerant requirements will vary with  
lenths). Check all joints for leaks. Purge nitrogen and R410A  
mixture. Correct any leaks and rechecks.  
Evacuation  
Evacuating the system of noncondensables is critical for  
proper operation of the unit. Noncondensables are defined  
as any gas that will not condense under temperatures and  
pressures present during operation of an air conditioning  
system. Noncondensables and water vapor combine with  
refrigerant to produce substances that corrode copper piping  
and compressor parts.  
Figure 12  
WARNING  
Refrigerant can be harmful if inhaled. Refrigerant must  
always be used and recovered responsibly. Incorrect  
or irresponsible use of refrigerant can result in personal  
injury or death.  
WARNING  
Do Not use a compressor to evacuate a system. Avoid  
deep vacuum operation. Extremely low vacuums can  
cause internal arcing and compressor failure. Danger  
of equipment damage. Damage caused by deep vacuum  
operation will void warranty.  
WARNING  
Never use oxygen to pressurize refrigeration or air  
conditioning systems. Oxygen will explode on contact  
with oil and could cause personal injury or death.  
Use a thermocouple or thermistor electronic vacuum gauge  
that is calibrated in microns. Use an instrument that reads  
down to 50 microns.  
1. Connect the manifold gauge set to the service valve ports  
as follows:  
Using an Electronic Leak Detector  
1. Connect the high pressure hose of the manifold gauge  
set to the suction valve service port. (Normally the high  
pressure hose is connected to the liquid line port; however,  
connecting it to the suction ports helps to protect the manifold  
gauge set from damage caused by high pressure.)  
Low pressure gauge to suction line service valve  
High pressure gauge to liquid line service valve.  
2. Connect micron gauge.  
2. With both manifold valves closed, connect the cylinder of  
R410A refrigerant. Open the valve on the R410A cylinder  
(vapor only).  
3. Connect the vacuum pump (with vacuum gauge) to the  
center port of the manifold gauge set.  
506469-01  
Issue 1008  
Page 11 of 24  
4. Open both manifold valves and start vacuum pump.  
5. Evacuate the line set and indoor unit to a minimum of  
500 microns or lower. During the early stages of evacuation,  
it is desirable to close the manifold gauge valve at least once  
to determine if there is a rapid rise in pressure. A rapid rise  
in pressure indicates a relatively large leak. If this occurs,  
the leak testing procedure must be repeated.  
6. When 500 microns or lower is maintained, close the  
manifold gauge valves, turn off the vacuum pump, and  
disconnect the manifold gauge center port hose from the  
vacuum pump. Attach the manifold gauge center port hose  
to a nitrogen cylinder with pressure regulator set to 150 psig  
and purge the hose. Open the manifold gauge valves to  
break the vacuum in the line set and indoor unit. Close the  
manifold gauge valves.  
7. Shut off the nitrogen cylinder and remove the manifold  
gauge hose from the cylinder. Open the manifold gauge  
valves to release the nitrogen from the line set and indoor  
unit.  
8. Reconnect the manifold gauge to the vacuum pump,  
turn the pump on, and continue to evacuate the line set and  
indoor unit until 500 microns is maintained within a 20 minute  
period after shutting off the vacuum pump and closing the  
manifold gauge valves.  
9. When the requirements above have been met, disconnect  
the manifold hose from the vacuum pump. Open the service  
valves to break the vacuum in the line set and indoor unit.  
506469-01  
Issue 1008  
Page 12 of 24  
Units are factory charged with the amount of R410A  
refrigerant indicated on the unit rating plate. This charge is  
based on a matching indoor coil and outdoor coil with 15’  
line set. For varying lengths of line set, refer to Table 5 for  
refrigerant charge adjustment. A blank space is provided  
on the unit rating plate to list the actual field charge.  
START-UP  
CAUTION  
If unit is equipped with a crankcase heater, it should be  
energized 24 hours before unit start-up to prevent  
compressor damage as a result of slugging.  
Refrigerant Charge Adjustment  
Liquid Line Set  
Diameter  
Oz. per 5 ft. adjust  
from 15 ft. line set*  
1. Rotate fan to check for frozen bearings or binding.  
2. Inspect all factory and field-installed wiring for loose  
connections.  
3 oz. Per 5 ft.  
3/8 in.  
* If line length is greater than 15 ft., add this amount.  
If line length is less than 15 ft., remove this amount.  
3. After evacuation is complete, open liquid line and suction  
line service valves to release refrigerant charge (contained  
in outdoor unit) into system.  
Table 5  
4. Replace the stem caps and secure finger tight, then  
tighten an additional 1/6 of a turn.  
IMPORTANT  
Mineral oils are not compatible with R410A. If oil must  
be added, it must be a polyolester oil.  
5. Check voltage supply at the disconnect switch. The  
voltage must be within the range listed on the unit nameplate.  
If not, do not start equipment until the power company has  
been consulted and the voltage condition corrected.  
If the system is void of refrigerant, clean the system using  
the procedure described below.  
6. Set thermostat for cooling demand, turn on power to  
indoor blower, and close the outdoor unit disconnect switch  
to start the unit.  
1. Use dry nitrogen to pressurized the system and check  
for leaks. Repair leaks, if possible.  
2. Evacuate the system to remove as much of the moisture  
as possible.  
7. Recheck unit voltage with unit running. Power must be  
within range shown on unit nameplate.  
3. Use dry nitrogen to break the vacuum.  
4. Evacuate the system again.  
Refrigerant Charging  
This system is charged with R410A refrigerant which  
operates at much higher pressures than R-22. The liquid  
line drier provided with the unit is approved for use with  
R410A. Do not replace it with one designed for use with R-  
22. This unit is NOT approved for use with coils which  
use capillary tubes as a refrigerant metering device.  
5. Weigh the appropriate amount of R410Arefrigerant (listed  
on unit nameplate) into the system.  
6. Monitor the system to determine the amount of moisture  
remaining in the oil. Use a test kit to verify that the moisture  
content is withing the kit’s dry color range. It may be  
necessary to replace the filter drier several times to achieve  
the required dryness level. If system dryness is not  
verified, the compressor will fail in the future.  
R410A refrigerant cylinders are rose colored. Refrigerant  
should be added through the suction valve in the liquid state.  
Certain R410A cylinders are identified as being equipped  
with a dip tube. These allow liquid refrigerant to be drawn  
from the bottom of the cylinder without inverting the cylinder.  
Do not turn this type of cylinder upside down to draw  
refrigerant.  
The outdoor unit should be charged during warm weather.  
However, applications arise in which charging must occur in  
the colder months. The method of charging is determined  
by the unit’s refrigerant metering device and the outdoor  
ambient temperature.  
Measure the liquid line temperature and the outdoor ambient  
temperature as outlined below:  
506469-01  
Issue 1008  
Page 13 of 24  
1. Connect the manifold gauge set to the service valve ports  
as follows (See Figure 13):  
Blocking Outdoor Coil  
Outdoor coil should be  
Low pressure gauge to suction line service valve  
High pressure gauge to liquid line service valve  
blocked one side at a time  
with cardboard or plastic  
sheet until proper testing  
pressures are reached  
2. Close manifold gauge set valves. Connect the center  
manifold hose to an upright cylinder of R410A.  
CARDBOARD OR  
PLASTIC SHEET  
3. If room temperature is below 70°F, set the room  
thermostat to call for heat. This will create the necessary  
load for properly charging the system in the cooling cycle.  
Figure 11  
4. Use a digital thermometer to record the outdoor ambient  
temperature.  
a ura on emper  
Liquid Line Tempera  
Subcooling Value °F  
_
°
°
5. When the heating demand has been satisfied, switch the  
thermostat to cooling mode with a set point of 68°F. When  
pressures have stabilized, use a digital thermometer to  
record the liquid and suction line temperatures.  
=
5. Compare the subcooling value with those shown in Table  
6 on page 14. If subcooling is greater than shown, recover  
some refrigerant. If subcooling is less than shown, add some  
refrigerant.  
6. The outdoor temperature will determine which charging  
method to use. Proceed with the appropriate charging  
method.  
Charge UsingApproach Method - Outdoor Temperatures  
65°F or Above  
Charge Using Subcooling Method - Outdoor  
Temperatures Below 65°F  
The following procedure is intended as a general guide and  
is for use on expansion valve systems only. For best results,  
indoor temperature should be 70°F to 80°F. Monitor system  
pressures while charging.  
When the outdoor ambient temperature is below 65°F, the  
subcooling method can be used to charge the unit. It may  
be necessary to restrict the air flow through the outdoor coil  
to achieve pressures in the 200-250 psig range. These  
higher pressures are necessary for checking the charge.  
Block equal sections of air intake panels and move  
obstructions sideways until the liquid pressure is in the 200-  
250 psig range (see Figure 11).  
1. Record outdoor ambient temperature using a digital  
thermometer.  
2. Attach high pressure gauge set and operate unit for  
several minutes to allow system pressures to stabilize.  
1. With the manifold gauge hose on the liquid service port  
and the unit operating stably, use a digital thermometer to  
record the liquid line temperature.  
3. Compare stabilized pressures with those provided in Table  
8 on page 15. Minor variations in these pressures may be  
expected due to differences in installations. Significant  
differences could mean that the system is not properly  
charged or that a problem exists with some component  
in the system. Pressures higher than those listed indicate  
that the system is undercharged. Verify adjusted charge  
using the approach method.  
2. At the same time, record the liquid line pressure reading.  
3. Use the temperature/pressure chart (Table 5 on page  
14) to determine the saturation temperature for the liquid  
line pressure reading.  
4. Subtract the liquid line temperature from the saturation  
temperature (according to the chart) to determine subcooling  
4. Use the same digital thermometer to check liquid line  
temperature.  
5. Subtract the outdoor ambient temperature from the liquid  
line temperature to determine the approach temperature.  
506469-01  
Issue 1008  
Page 14 of 24  
R410A Temperature/Pressure Chart  
Subcooling Values  
Temp.  
(F  
Pressure  
Psig  
Temp.  
(F  
Pressure  
Psig  
Temp.  
(F  
Pressure  
Psig  
32  
33  
100.8  
102.9  
74  
75  
214.0  
217.4  
116  
117  
396.0  
401.3  
34  
35  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
46  
47  
48  
49  
50  
51  
52  
53  
54  
55  
56  
57  
58  
59  
60  
61  
62  
63  
64  
65  
66  
67  
68  
69  
70  
71  
72  
73  
105.0  
107.1  
109.2  
111.4  
113.6  
115.8  
118.0  
120.3  
122.6  
125.0  
127.3  
129.7  
132.2  
134.6  
137.1  
139.6  
142.2  
144.8  
147.4  
150.1  
152.8  
155.5  
158.2  
161.0  
163.9  
166.7  
169.6  
172.6  
175.5  
178.5  
181.6  
184.3  
187.7  
190.9  
194.1  
197.3  
200.6  
203.9  
207.2  
210.6  
76  
77  
220.9  
224.4  
228.0  
231.6  
235.3  
239.0  
242.7  
246.5  
250.3  
254.1  
258.0  
262.0  
266.0  
270.0  
274.1  
278.2  
282.3  
286.5  
290.3  
295.1  
299.4  
303.8  
308.2  
312.7  
317.2  
321.8  
326.4  
331.0  
335.7  
340.5  
345.3  
350.1  
355.0  
360.0  
365.0  
370.0  
375.1  
380.2  
385.4  
390.7  
118  
119  
120  
121  
122  
123  
124  
125  
126  
127  
128  
129  
130  
131  
132  
133  
134  
135  
136  
137  
138  
139  
140  
141  
142  
143  
144  
145  
146  
147  
148  
149  
150  
151  
152  
153  
154  
155  
406.7  
412.2  
417.7  
423.2  
428.8  
434.5  
440.2  
445.9  
451.8  
457.6  
463.5  
469.5  
475.6  
481.6  
487.8  
494.0  
500.2  
506.5  
512.9  
519.3  
525.8  
532.4  
539.0  
545.6  
552.3  
559.1  
565.9  
572.8  
579.8  
586.8  
593.8  
601.0  
608.1  
615.4  
622.7  
630.1  
637.5  
645.0  
Table 7  
78  
79  
80  
°
°
°
Saturation Temperature °F  
Liquid Line Temperature °F  
Subcooling Value °F  
81  
_
82  
=
83  
84  
85  
6. Compare the approach value with those shown in Table  
7. If the values do not agree with those provided in Table 7,  
add refrigerant to lower the approach temperature or recover  
refrigerant from the system to increase the approach  
temperature.  
86  
87  
88  
89  
90  
91  
Approach Values for TXV Systems  
92  
93  
94  
95  
96  
97  
98  
Approach value is the liquid line temperature minus  
the outdoor ambient temperature (± 1°F).  
99  
100  
101  
102  
103  
104  
105  
106  
107  
108  
109  
110  
111  
112  
113  
114  
115  
Note: For best results, use the same digital  
thermometer to check both outdoor ambient and  
liquid temperatures.  
Table 8  
Check Charge Using Normal Operating Pressures  
Use Table 8 to perform maintenance checks. Table 8 is not  
a procedure for charging the system. Minor variations in  
these pressures may be due to differences in installations.  
Significant deviations could mean that the system is not  
properly charged or that a problem exists with some  
component in the system.  
°
°
°
Liquid Line Temperature °F  
Outdoor Ambient Temperature °F  
Approach Temperature °F  
_
=
72  
73  
207.2  
210.6  
114  
115  
385.4  
390.7  
Table 6  
506469-01  
Issue 1008  
Page 15 of 24  
Table 8  
506469-01  
Issue 1008  
Page 16 of 24  
Thermostat Demand Wiring  
OPERATION  
The diagnostic module requires a thermostat demand signal  
to operate properly. The thermostat demand signal input,  
labeled Y on the module, should always be connected to  
the compressor contactor coil so that when the coil is  
energized, the demand signal input is 24VAC. When the  
Coil is not energized, the demand signal input should be  
less than 0.5VAC.  
Outdoor unit and indoor blower cycle on demand from the  
room thermostat. When the thermostat blower switch is  
moved to the ON position, the indoor blower operates  
continuously.  
System Diagnostic Module  
4AC18LT units contain a diagnostic module for  
troubleshooting air conditioning system failures. By  
monitoring and analyzing data from the compressor and  
thermostat demand, the module can accurately detect the  
cause of electrical and system related failure without any  
sensors. If a system problem occurs, a flashing LED  
indicator communicates the failure code.  
Miswired Module Codes  
Depending on the system configuration, someALERT flash  
codes may not be active. The presence of safety switches  
affects how the system alerts are displayed by the module.  
Miswiring the diagnostic module will cause false LED codes.  
Table 11 on page 19 describes LED opeation when the  
module is miswired and what troubleshooting action is  
required to correct the problem.  
LED Description  
POWER LED (Green) indicates voltage is present at the  
power connection of the module.  
ALERT LET (Yellow) communicates an abnormal system  
condition through a unique flash code. TheALERT LED will  
flash a number of times consecutively, pause, and then  
repeat the process. The number of consecutive flashes  
correlates to a particular abnormal condition.  
TRIP LED (Red) indicates there is a demand signal from  
the thermostat but no current to the compressor is detected  
by the module. The TRIP LED typically indicates the  
compressor protector is open or may indicate missing supply  
power to the compressor.  
Interpreting the Diagnostic LEDs  
When an abnormal system condition occurs, the diagnostic  
module displays the appropriate ALERT and/or TRIP LED.  
The yellow ALERT LED will flash a number of times  
consecutively, pause, and then repeat the process. To  
identify a flash code number, count the number of  
consecutive flashes. Refer to Table 9 on page 18 and Table  
10 on page 19 for information on the flash codes.  
Every time the module powers up, the lastALERT LED flash  
code that occurred prior to shutdown is displayed for 60  
seconds. The module will continue to display the previous  
flash code until the condition returns to normal or 24 VAC is  
removed from the module. TRIP andALERT LEDs flashing  
at the same time means control circuit voltage is too low for  
operation.  
24 VAC Power Wiring  
The diagnoctic module requires a constant nominal 24VAC  
power supply. The wiring to the module’s R and C terminals  
must be directly from the indoor unit or thermostat.  
506469-01  
Issue 1008  
Page 17 of 24  
Flash Codes  
Table 9  
506469-01  
Issue 1008  
Page 18 of 24  
Flash Codes (cont.)  
Table 10  
506469-01  
Issue 1008  
Page 19 of 24  
Miswired Module Troubleshooting  
Table 11  
506469-01  
Issue 1008  
Page 20 of 24  
4. Check all wiring for loose connections.  
MAINTENANCE  
WARNING  
5. Check for correct voltage at unit (with unit operating).  
6. Check amp-draw on belower motor.  
Unit nameplate_____________ Actual _________  
Before performing maintenance operations on system,  
turn the electric power to unit OFF at disconnect  
switch(es). Unit may have multiple power supplies.  
Electrical shock could cause personal injury or death.  
Maintenance and service must be performed by a qualified  
installer or service agency.  
At the beginning of each cooling season, the system should  
be checked as follows:  
1. Clean and inspect condenser coil. Coil may be flushed  
witha a water hose. Be sure the power is off before usig  
water to clean the coil.  
2. Outdoor fan motor is pre-lubricated and sealed. No further  
lubrication is needed.  
3. Visually inspect connecting lines and coils for evidence  
of oil leaks.  
4. Check wiring for loose connections.  
5. Check for correct voltage at unit (with unit operating).  
6. Check amp-draw outdoor fan motor.  
Unit nameplate ____________ Actual __________  
NOTE: If owner complains of insufficient cooling, the  
unit should be gauged and refrigerant charge checked. Refer  
to the Refrigerant Charging section on page 12.  
Indoor Coil  
1. Clean coil, if necessary.  
2. Check connecting lines and coils for evidence of oil leaks.  
3. Check condensate pan line and clean, if necessary.  
Indoor Unit  
1. Clean or change filters.  
2. Adjust blower speed for cooling. Measure the pressure  
drop over the coil to determine the correct blower CFM.  
3. Belt drive blowers: Check belt for wear and proper  
tension.  
506469-01  
Issue 1008  
Page 21 of 24  
Start-Up and Performance Checklist  
Job Name _____________________________  
Job No. ____________  
City _______________  
City _______________  
Date ___________  
State ___________  
State ___________  
Job Location ___________________________  
Installer _______________________________  
Unit Model No. _________________________  
Service Technician _______________________  
Serial No._____________________________  
Nameplate Voltage _____________________  
Rated Load Ampacity _________  
Maximum Fuse or Circuit Breaker ________________________  
Electical Connections Tight? Indoor Filter Clean? Supply Voltage (Unit Off) __________  
Compressor Amperage ________ Outdoor Fan __________  
Indoor Blower RPM ___________________ S.P. Drop Over Indoor (Dry) ____________________  
Outdoor Coil Entering Air Temperature ________ Voltage with Compressor Operating __________  
Discharge Pressure __________________ Vapor Pressure ____________  
Refrigerant Charge Checked?  
Refrigerant Lines: Leak Checked?  
Service Valves: Fully Opened?  
Outdoor Fan Checked?  
Properly Insulated?  
Caps Tight?  
Thermostat: Calibrated?  
Properly Set?  
Level?  
506469-01  
Issue 1008  
Page 22 of 24  
WIRE DIAGRAM  
506469-01  
Issue 1008  
Page 23 of 24  
NOTES  
506469-01  
Issue 1008  
Page 24 of 24  

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