Allied Lennox 4AC16LT Series User manual

506467-01 Page 1 of 20Issue 1827
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INSTALLATION INSTRUCTIONS
4AC16LT SERIES
Split System Air Conditioner
(P) 506467-01
*P506467-01*
Manufactured By
Allied Air Enterprises LLC
A Lennox International, Inc. Company
215 Metropolitan Drive
West Columbia, SC 29170
This manual must be left with the homeowner for future reference.
This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in
manuals, be alert to the potential for personal injury or death.
Installation and servicing of air conditioning equipment
can be hazardous due to internal refrigerant pressure
and live electrical components. Only trained and
qualied service personnel should install or service
this equipment. Installation and service performed by
unqualied persons can result in property damage,
personal injury, or death.
WARNING
The equipment covered in this manual is to be installed
by trained and experienced service and installation
technicians. Improper installation, modication, service,
or use can cause electrical shock, re, 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
ELECTRICAL SHOCK HAZARD!
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 in property damage, personal
injury, or death.
WARNING
Sharp metal edges can cause injury. When installing
the unit, use care to avoid sharp edges.
WARNING
Table of Contents
Installation ...................................................................2
Start-Up .....................................................................10
Operation...................................................................14
Maintenance..............................................................18

Page 2 of 20 506467-01Issue 1827
Installation
General
Read this entire instruction manual, as well as the
instructions supplied in separate equipment, before
starting the installation. Observe and follow all warnings,
cautions, instructional labels, and tags. Failure to comply
with these instructions could result in an unsafe condition
and/or premature component failure.
These instructions are intended as a general guide only
for use by qualied personnel and do not supersede any
national or local codes in any way. The installation must
comply with all provincial, state, and local codes as well as
the National Electrical Code (U.S.) or Canadian Electrical
Code (Canada). Compliance should be determined prior
to installation.
4AC16LT condensing units use R410A which is an ozone-
friendly HFC refrigerant. The unit must be installed with
a matching indoor coil and line set. 4AC16LT units are
designed for use in expansion valve (TXV) systems only.
A lter drier approved for use with R410A is installed in
the unit.
NOTE: This product has been designed and manufactured
to meet ENERGY STAR criteria for energy efciency when
matched with appropriate coil components. However,
proper refrigerant charge and proper air ow are critical
to achieve rated capacity and efciency. Installation of
this product should follow the manufacturer’s refrigerant
charging and air ow instructions. Failure to conrm
proper charge and airow may reduce energy efciency
and shorten equipment life.
When servicing or repairing HVAC components, ensure
the fasteners are appropriately tightened. Table 1 shows
torque values for fasteners.
Table 1. Torque Table
Fastener Torque
Stem Caps 8 ft. lbs.
Service Port Caps 8 ft. lbs.
Sheet Metal Screws 16 in. lbs.
#8 Machine Screws 16 in. lbs.
#10 Machine Screws 28 in. lbs.
Compressor Bolts 90 in. lbs.
Inspection of Shipment
Upon receipt of equipment, carefully inspect it for possible
shipping damage. If damage is found, it should be noted
on the carrier’s freight bill. Take special care to examine
the unit inside the carton if the carton is damaged. Any
concealed damage discovered should be reported to the
last carrier immediately, preferably in writing, and should
include a request for inspection by the carrier’s agent. If
any damages are discovered and reported to the carrier
DO NOT INSTALL THE UNIT, as claim may be denied.
Check the unit rating plate to conrm specications are as
ordered.
Location of Unit
Refer to Figure 1 for installation clearances.
Figure 1. Installation Clearances
* A service clearance of 30” must be maintained on one of the
sides adjacent to the control box. Clearance to one of the other
three sides must be 36”. Clearance to one of the remaining two
sides may be 12” and the nal side may be 6”.
A clearance of 24” must be maintained between units.
48” clearance required on top of unit. Maximum soft overhang is
36”.
Slab Mounting
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 (Figure 2).
Roof Mounting
Install unit at a minimum of 4” above surface of the roof.
Care must be taken to ensure weight of unit is properly
distributed over roof joists and rafters. Either redwood or
steel supports are recommended.
Figure 2. Slab Mounting

506467-01 Page 3 of 20Issue 1827
Electrical Wiring
All eld 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.
Unit must be grounded in accordance with national and
local codes. Failure to ground unit properly can result in
personal injury or death.
WARNING
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.
1. Install line voltage power supply to unit from a properly
sized disconnect switch. Any excess high voltage eld
wiring should be trimmed or secured away from the
low voltage eld wiring.
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 tting. Units are approved for
use only with copper conductors. 24V Class II circuit
connections are made in the low voltage junction box.
A complete unit wiring diagram is located inside the
unit control box cover.
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 (Figure 3).
Figure 3. Thermostat Designations
See unit wiring diagram for power supply connections.
If the indoor unit is not equipped with a blower relay, one must be
eld supplied and installed.
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.
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 separation of eld-installed low and
high voltage circuits.
Refrigerant Piping
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
If the 4AC16LT 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 ushed 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 4AC16LT unit.
Field refrigerant piping consists of liquid and suction lines
from the outdoor unit (sweat connections) to the indoor
coil (are or sweat connections).
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. Table 2 shows
the diameters for line sets up to 100’ although vertical
lift applications and trapping requirements need to be
reviewed for line sets over 50’; refer to long line set
guidelines.
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 oor) 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.
Following are some points to consider when placing and
installing a high-efciency outdoor unit:

Page 4 of 20 506467-01Issue 1827
If ANY refrigerant tubing is required to be buried by state
or local codes, provide a 6 inch vertical rise at service
valve.
CAUTION
Placement
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 very high level of sound transmission. Figure 4
shows how to place the outdoor unit and line set to reduce
line set vibration.
Line Set Isolation
The following illustrations demonstrate procedures that
ensure proper refrigerant line set isolation. Figure 5 shows
how to install line sets on horizontal runs. Figure 6 shows
how to make a transition from horizontal to vertical. Figure
7 shows how to install line sets on vertical runs.
Table 2. Refrigerant Line Set Diameters (in.)
Liquid Line
Btuh Line Set Length and Size
12 ft. 25 ft. 50 ft. 75 ft. 100 ft.
24,000 3/8 3/8 3/8 3/8 3/8
36,000 3/8 3/8 3/8 3/8 1/2
48,000 3/8 3/8 3/8 1/2 1/2
60,000 3/8 3/8 3/8 1/2 1/2
Suction Line
Btuh Line Set Length and Size
12 ft. 25 ft. 50 ft. 75 ft. 100 ft.
24,000 3/4 3/4 3/4 3/4 7/8
36,000 7/8 7/8 7/8 7/8 1-1/8
48,000 7/8 7/8 7/8 1-1/8 1-1/8
60,000 1-1/8 1-1/8 1-1/8 1-1/8 1-1/8
For lines longer than 50 ft., refer to long line set guidelines.
Brazing Connection Procedure
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.
4. Remove the Schrader core assemblies before brazing
to protect them from damage due to extreme heat.
Replace the cores when brazing is complete.
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.
Figure 4. Outside Unit Placement & Installation
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 tting during nal assembly to
ensure proper seating, sealing, and rigidity.
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 section).
When ushing 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
ush system as explained in these instructions will void
warranty.
CAUTION

506467-01 Page 5 of 20Issue 1827
Figure 5. Refrigerant Line Sets: Installing Horizontal Runs
Figure 6. Refrigerant Line Sets: Transition from Vertical to Horizontal

Page 6 of 20 506467-01Issue 1827
Figure 7. Refrigerant Line Sets: Installing Vertical Runs (new construction shown)
NOTE: Similar installation practices
should be used if line set is to be installed
on exterior of outside wall.
Figure 8. Flushing Connections

506467-01 Page 7 of 20Issue 1827
Flushing Existing Line Set and Indoor Coil
This procedure should not be performed on systems
that contain contaminants, such as compressor burn
out.
Required Equipment
The following equipment is needed to ush the existing
line set and indoor coil (Figure 8). 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).
Flushing Procedure
NOTE: The line set and/or indoor coil must be ushed with
at least the same amount of refrigerant that previously
charged the system. Check the charge in the ushing
cylinder before ushing the unit.
1. Remove existing R-22 refrigerant using the appropriate
procedure.
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 ush the system:
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 conrm that the entire system is completely
void of refrigerant. Disconnect the liquid and suction lines
from the existing outdoor unit.
If the existing outdoor unit is equipped with manual shutoff
valves AND new R-22 refrigerant will be used to ush 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.
(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 conrm
that the valves are not allowing refrigerant to ow back
into the low side of the system. Disconnect the liquid and
suction lines from the existing outdoor unit.
2. Remove the existing outdoor unit. Set the new R410A
unit and follow the brazing connection procedure
outlined previously to make line set connections. Do
not install the R410A thermal expansion valve at this
time.
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.
4. Remover the existing R-22 refrigerant ow control
orice or thermal expansion valve before continuing
with ushing procedures. R-22 ow control devices
are not approved for use with R410A refrigerant and
may prevent proper ushing. Use a eld-provided
tting to reconnect the lines.
5. Remove the pressure tap valve cores from the
4AC16LT 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 machine 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 ow 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 system.
NOTE: A single system ush should remove all of
the mineral oil from the existing refrigerant lines and
indoor coil. A second ushing may be done (using
clean refrigerant) if insufcient amounts of mineral oil
were removed during the rst ush. After each system
ush, allow the recovery machine to pull a vacuum on
the system at the end of the procedure.
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.
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 4AC16LT
unit’s service valves.
11. Install the refrigerant expansion valve approved for
use with R410A refrigerant in the liquid line at the
indoor coil.
Refrigerant Metering Device
4AC16LT units are designed for use with TXV systems
only.
Expansion valves equipped with Chatleff-type ttings are
available from the manufacturer. See Table 3 for proper
TXV for each unit.

Page 8 of 20 506467-01Issue 1827
Capacity Part Number
4AC16LT -24, -36 A4TXV01
4AC16LT -48 A4TXV02
4AC16LT -60 H4TXV03
Table 3.
To install an expansion valve (see Figure 9):
1. Separate the distributor assembly and remove the
piston orice and used Teon seal. Insert nozzle end
of the expansion valve along with a new Teon seal
into the distributor and tighten to 20 - 30 ft. lbs. Use
backup wrench on all wrench ats. Over-tightening
will crush the Teon seal and may cause a leak.
2. Attach liquid line portion of distributor assembly along
with new Teon seal to the inlet of the expansion
valve. Tighten to 20 - 30 ft. lbs. Use backup wrench on
all wrench ats. Over-tightening will crush the Teon
seal and may cause a leak.
3. Connect the external equalizer line to the equalizer
port on the suction line and tighten to 8 ft. lbs.
4. Strap the superheat sensing bulb to the suction
header.
If installing an expansion valve on an indoor coil that
previously used a xed orice, be sure to remove the
existing xed orice. Failure to remove a xed orice when
installing an expansion valve to the indoor coil will result in
improper operation and damage to the system.
Manifold Gauge Set
Manifold gauge 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 (Figure 9)
and service ports are used for leak testing, evacuation,
charging, and checking charge.
Each valve is equipped with a service port which has a
factory-installed Schrader valve.A service 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 nger tight, then an additional 1/6 turn.
To Open Liquid or Suction Line Service Valve
1. Remove stem cap with an adjustable wrench.
2. 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.
3. Replace the stem cap. Tighten nger 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.
2. Use a service wrench with a hex-head extension to
turn the stem clockwise to seat the valve. Tighten
rmly.
3. Replace the stem cap. Tighten nger tight, then
tighten an additional 1/6 turn.
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
(Figure 10).
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
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.

506467-01 Page 9 of 20Issue 1827
Figure 9.
Figure 10.
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
Never use oxygen to pressurize refrigeration or air
conditioning systems. Oxygen will explode on contact
with oil and could cause personal injury or death.
WARNING
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.)
2. With both manifold valves closed, connect the cylinder
of R410A refrigerant. Open the valve on the R410A
cylinder (vapor only).
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 length). Check all joints for leaks. Purge
nitrogen and R410A mixture. Correct any leaks and
rechecks.
Evacuation
Evacuating the system of non-condensables is critical for
proper operation of the unit. Non-condensables are dened
as any gas that will not condense under temperatures and
pressures present during operation of an air conditioning
system. Non-condensables and water vapor combine with
refrigerant to produce substances that corrode copper
piping and compressor parts.

Page 10 of 20 506467-01Issue 1827
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
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:
• Low pressure gauge to suction line service valve
• High pressure gauge to liquid line service valve.
2. Connect micron gauge.
3. Connect the vacuum pump (with vacuum gauge) to
the center port of the manifold gauge set.
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.
Start-Up
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.
CAUTION
1. Rotate fan to check for frozen bearings or binding.
2. Inspect all factory and eld-installed wiring for loose
connections.
3. After evacuation is complete, open liquid line and
suction line service valves to release refrigerant
charge (contained in outdoor unit) into system.
4. Replace the stem caps and secure nger tight, then
tighten an additional 1/6 of a turn.
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.
6. Set thermostat for cooling demand, turn on power to
indoor blower, and close the outdoor unit disconnect
switch to start the unit.
7. Recheck unit voltage with unit running. Power must
be within range shown on unit nameplate.
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.
R410A refrigerant cylinders are rose colored. Refrigerant
should be added through the suction valve in the liquid
state.
Certain R410A cylinders are identied 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.
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 4 for
refrigerant charge adjustment. A blank space is provided
on the unit rating plate to list the actual eld charge.

506467-01 Page 11 of 20Issue 1827
Table 4. Refrigerant Charge Adjustment
Liquid Line Set Diameter Oz. per 5 ft. Adjust from 15
ft. Line Set*
3/8 in. 3 oz. per 5 ft.
* If line length is greater than 15 ft., add this amount. If line
length is less than 15 ft., remove this amount.
Mineral oils are not compatible with R410A. If oil must
be added, it must be a polyolester oil.
IMPORTANT
If the system is void of refrigerant, clean the system using
the procedure described below.
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.
3. Use dry nitrogen to break the vacuum.
4. Evacuate the system again.
5. Weigh the appropriate amount of R410A refrigerant
(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 lter drier
several times to achieve the required dryness level. If
system dryness is not veried, the compressor will fail
in the future.
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:
1. Connect the manifold gauge set to the service valve
ports as follows (Figure 9 or Figure 10):
• Low pressure gauge to suction line service valve
• High pressure gauge to liquid line service valve
2. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of R410A.
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.
4. Use a digital thermometer to record the outdoor
ambient temperature.
5. When the heating demand has been satised, 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.
6. The outdoor temperature will determine which
charging method to use. Proceed with the appropriate
charging method.
Charge Using Subcooling Method - Outdoor
Temperatures Below 65°F
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 ow 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 (Figure 11).
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.
2. At the same time, record the liquid line pressure
reading.
3. Use the temperature/pressure chart (Table 7) 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
Figure 11. Blocking Outdoor Coil
Outdoor coil should be
blocked one side at a time
with cardboard or plastic
sheet until proper testing
pressures are reached
°Saturation Temperature °F
-°Liquid Line Temperature °F
=°Subcooling Value °F
5. Compare the subcooling value with those shown in
Table 5. If subcooling is greater than shown, recover
some refrigerant. If subcooling is less than shown,
add some refrigerant.
Charge Using Approach Method - Outdoor
Temperatures 65°F or Above
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.

Page 12 of 20 506467-01Issue 1827
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.
3. Compare stabilized pressures with those provided
in Table 8. Minor variations in these pressures may
be expected due to differences in installations.
Signicant 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.
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.
Capacity -24 -36 -48 -60
Temp °F 12 11 9.5 7
Table 5. Subcooling Values
°Liquid Line Temperature °F
-
°Outdoor Ambient
Temperature °F
=°Approach Temperature °F
6. Compare the approach value with those shown in
Table 6. If the values do not agree with those provided
in Table 6, add refrigerant to lower the approach
temperature or recover refrigerant from the system to
increase the approach temperature.
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.
Signicant deviations could mean that the system is not
properly charged or that a problem exists with some
component in the system.
Capacity -24 -36 -48 -60
Temp °F 4556
Approach value is the liquid line temperature minus the
outdoor ambient temperature (±1°F).
NOTE: For best results, use the same digital thermometer to
check both outdoor ambient and liquid temperatures.
Table 6. Approach Values for TXV Systems
Temp
°F
Pressure
psig
Temp
°F
Pressure
psig
Temp
°F
Pressure
psig
32 100.8 74 214.0 116 396.0
33 102.9 75 217.4 117 401.3
34 105.0 76 220.9 118 406.7
35 107.1 77 224.4 119 412.2
36 109.2 78 228.0 120 417.7
37 111.4 79 231.6 121 423.2
38 113.6 80 235.3 122 428.8
39 115.8 81 239.0 123 434.5
40 118.0 82 242.7 124 440.2
41 120.3 83 246.5 125 445.9
42 122.6 84 250.3 126 451.8
43 125.0 85 254.1 127 457.6
44 127.3 86 258.0 128 463.5
45 129.7 87 262.0 129 469.5
46 132.2 88 266.0 130 475.6
47 134.6 89 270.0 131 481.6
48 137.1 90 274.1 132 487.8
49 139.6 91 278.2 133 494.0
50 142.2 92 282.3 134 500.2
51 144.8 93 286.5 135 506.5
52 147.4 94 290.3 136 512.9
53 150.1 95 295.1 137 519.3
54 152.8 96 299.4 138 525.8
55 155.5 97 303.8 139 532.4
56 158.2 98 308.2 140 539.0
57 161.0 99 312.7 141 545.6
58 163.9 100 317.2 142 552.3
59 166.7 101 321.8 143 559.1
60 169.6 102 326.4 144 565.9
61 172.6 103 331.0 145 572.8
62 175.5 104 335.7 146 579.8
63 178.5 105 340.5 147 586.8
64 181.6 106 345.3 148 593.8
65 184.3 107 350.1 149 601.0
66 187.7 108 355.0 150 608.1
67 190.9 109 360.0 151 615.4
68 194.1 110 365.0 152 622.7
69 197.3 111 370.0 153 630.1
70 200.6 112 375.1 154 637.5
71 203.9 113 380.2 155 645.0
72 207.2 114 385.4
73 210.6 115 390.7
Table 7. R410A Temperature / Pressure Chart

506467-01 Page 13 of 20Issue 1827
Table 8.
Normal Operating Pressures
Low Capacity
Outdoor Coil
Entering Air
Temp. °F
-24 -36 -48 -60
L S L S L S L S
65 205 140 203 139 196 142 236 132
75 247 142 242 141 240 144 278 136
85 288 145 287 144 294 149 321 140
95 330 147 344 147 348 150 360 144
105 372 148 391 149 402 151 405 148
115 413 151 438 153 456 154 447 152
High Capacity
Outdoor Coil
Entering Air
Temp. °F
-24 -36 -48 -60
L S L S L S L S
65 212 137 210 141 237 137 248 123
75 254 139 247 143 266 139 293 128
85 295 142 298 145 330 140 337 132
95 337 144 335 147 374 142 382 137
105 379 146 400 149 418 144 427 142
115 424 149 451 151 462 145 471 146

Page 14 of 20 506467-01Issue 1827
Operation
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
4AC16LT 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 ashing LED
indicator communicates the failure code.
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 ash code. The ALERT LED
will ash a number of times consecutively, pause, and then
repeat the process. The number of consecutive ashes
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 ash a number of
times consecutively, pause, and then repeat the process.
To identify a ash code number, count the number of
consecutive ashes. Refer to Table 9 for information on
the ash codes.
Every time the module powers up, the last ALERT LED
ash code that occurred prior to shutdown is displayed
for 60 seconds. The module will continue to display the
previous ash code until the condition returns to normal
or 24 VAC is removed from the module. TRIP and ALERT
LEDs ashing at the same time means control circuit
voltage is too low for operation.
24 VAC Power Wiring
The diagnostic 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.
Thermostat Demand Wiring
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.
Mis-wired Module Codes
Depending on the system conguration, some ALERT
ash codes may not be active. The presence of safety
switches affects how the system alerts are displayed by
the module.
Mis-wiring the diagnostic module will cause false LED
codes. Table 10 describes LED operation when the module
is mis-wired and what troubleshooting action is required to
correct the problem.

506467-01 Page 15 of 20Issue 1827
LED Status Fault Description Troubleshooting Information
POWER
(Green)
Module has power Supply voltage is present at module terminals
TRIP
(Red)
Thermostat demand signal
Y1 is present, but the
compressor is not running
1. Compressor protector is open
• Check for high head pressure
• Check compressor supply voltage
2. Outdoor unit power disconnect is open
3. Compressor circuit breaker or fuse(s) is open
4. Broken wire or connector is not making contact
5. Low pressure switch open if present in system
6. Compressor contactor has failed open
ALERT
(Yellow)
Flash Code 1
Long Run Time
Compressor is running
extremely long run cycles
(Not applicable on heat
pump models)
--
ALERT
(Yellow)
Flash Code 2
System Pressure Trip
Discharge or suction
pressure out of limits or
compressor overloaded
1. High head pressure
• Check high pressure switch if present in system
• Check if system is overcharged with refrigerant
• Check for non-condensable in system
2. Condenser coil poor air circulation (dirty, blocked, damaged)
3. Condenser fan is not running
• Check fan capacitor
• Check fan wiring and connectors
• Check fan motor for failure or blockage
4. Return air duct has substantial leakage
5. If low pressure switch present in system, check Flash Code 1 information
ALERT
(Yellow)
Flash Code 3
Short Cycling
Compressor is running only
briey
1. Thermostat demand signal is intermittent
2. Time delay relay or control board defective
3. If high pressure switch present, go to Flash Code 2 information
4. If low pressure switch present, go to Flash Code 1 information
ALERT
(Yellow)
Flash Code 4
Locked Rotor 1. Run capacitor has failed
2. Low line voltage (contact utility if voltage at disconnect is low)
• Check wiring connections
3. Excessive liquid refrigerant in compressor
4. Compressor bearing are seized
5. Measure compressor oil level
Table 9. Flash Codes
Flash Codes

Page 16 of 20 506467-01Issue 1827
LED Status Fault Description Troubleshooting Information
ALERT
(Yellow)
Flash Code 5
Open Circuit 1. Outdoor unit power disconnect is open
2. Compressor circuit breaker or fuse(s) is open
3. Compressor contactor has failed open
• Check compressor contactor wiring and connectors
• Check for compressor contactor failure (burned, pitted, or open)
• Check wiring and connectors between supply and compressor
• Check for low pilot voltage at compressor contactor coil
4. High pressure switch is open and requires manual reset
5. Open circuit in compressor supply wiring or connections
6. Unusually long compressor protector reset time due to extreme ambient temperature
7. Compressor windings are damaged
• Check compressor motor winding resistance
ALERT
(Yellow)
Flash Code 6
Open Start Circuit
Current only in run circuit
1. Run capacitor has failed
2. Open circuit in compressor start wiring or connections
• Check wiring and connectors between supply and the compressor S terminal
3. Compressor start winding is damaged
• Check compressor motor winding resistance
ALERT
(Yellow)
Flash Code 7
Open Run Circuit
Current only in start circuit
1. Open circuit in compressor run wiring or connections
• Check wiring and connectors between supply and the compressor R terminal
2. Compressor run winding is damaged
• Check compressor motor winding resistance
ALERT
(Yellow)
Flash Code 8
Welded Contactor
Compressor always runs
1. Compressor contactor has failed closed
2. Thermostat demand signal not connected to module
ALERT
(Yellow)
Flash Code 9
Low Voltage
Control circuit less than
17VAC
1. Control circuit transformer is overloaded
2. Low line voltage (contact utility if voltage at disconnect is low)
• Check wiring conditions
Table 9. Flash Codes

506467-01 Page 17 of 20Issue 1827
Mis-wired Module Troubleshooting
Mis-wired Module Indication Recommended Troubleshooting Action
Green LED is not on; module
does not power up
Determine if both R and C module terminals are connected. Verify voltage is present at module’s R
and C terminals. Review 24VAC Power Wiring section for R and C wiring.
Green LED intermittent;
module powers up only when
compressor runs.
Determine if R and Y terminals are wired in reverse. Verify module’s R and C terminals have a
constant source. Review 24VAC Power Wiring section for R and C wiring.
TRIP LED is on, but system
and compressor check OK.
Verify Y terminal is connected to 24VAC at contactor coil. Verify voltage at contactor coils falls below
0.5VAC when off.
TRIP LED and ALERT LED
ashing together. Verify R and C terminals are supplied with 19-28VAC.
ALERT Flash Code 3
(compressor short cycling)
displayed incorrectly.
Verify Y terminal is connected to 24VAC at contactor coil. Verify voltage at contactor coil falls below
0.5VAC when off.
ALERT Flash Code 5, 6, or
7 (open circuit, open start
circuit, or open run circuit)
displayed incorrectly.
Check that compressor run and start wires are through module’s current sensing holes. Verify Y
terminal is connected to 24VAC at contactor coil. Verify voltage at contactor coil falls below 0.5VAC
when off.
ALERT Flash Code 6 (open
start circuit) displayed for
Code 7 (open run circuit) or
vice versa.
Check that compressor run and start wires are routed through the correct module sensing holes.
ALERT Flash Code 8
(welded contactor) displayed
incorrectly.
Determine if module’s Y terminal is connected. Verify Y terminal is connected to 24VAC at contactor
coil. Verify 24 VAC is present across Y and C when the thermostat demand signal is present. If not,
R and C are reverse wired. Verify voltage at contactor coil falls below 0.5VAC when off. Review
Thermostat Demand Wiring for Y and C wiring.
Table 10. Mis-wired Module Troubleshooting

Page 18 of 20 506467-01Issue 1827
Maintenance
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.
WARNING
Maintenance and service must be performed by a qualied
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 ushed
with a water hose. Be sure the power is off before
using 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 insufcient cooling, the unit
should be gauged and refrigerant charge checked. Refer
to the Refrigerant Charging section.
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 lters.
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.
4. Check all wiring for loose connections.
5. Check for correct voltage at unit (with unit operating).
6. Check amp-draw on blower motor.
Unit nameplate_____________ Actual _________

506467-01 Page 19 of 20Issue 1827
Start-Up and Performance Checklist
Job Name: ______________________________________________ Job No. _________________ Date: ________________
Job Location: ____________________________________________ City: ____________________ State: ________________
Installer: ________________________________________________ City: ____________________ State: ________________
Unit Model No. ___________________________________________ Serial No. _______________________________________
Service Technician: _______________________________________ Nameplate Voltage: _______________________________
Rated Load Ampacity: ________________ Compressor Amperage: _________________ Outdoor Fan: ____________________
Maximum Fuse or Circuit Breaker: ____________________________
Electrical Connections Tight? Indoor Filter Clean? Supply Voltage (Unit Off): ___________________________
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? Outdoor Fan Checked?
Refrigerant Lines: Leak Checked? Properly Insulated?
Service Valves: Fully Opened? Caps Tight?
Thermostat: Calibrated? Properly Set? Level?

Page 20 of 20 506467-01Issue 1827
Figure 12. Wiring Diagram