INSTALLATION AND MAINTENANCE
INSTRUCTIONS
2SCU13 Series
Split System Air Conditioner
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
INSTALLATION ...................................... 2
servicing any portion of the system. Failure
to disconnect power supplies can result in
property damage, personal injury, or death.
OPERATION ........................................ 14
START-UP............................................ 10
MAINTENANCE ................................... 14
WARNING
Installation and servicing of air conditioning
equipment can be hazardous due to internal
refrigerant pressure and live electrical com-
ponents. Only trained and qualified service
personnel should install or service this equip-
ment. Installation and service performed by
unqualified persons can result in property
damage, personal injury, or death.
CONNECTION DIAGRAMS ................. 16
WARRANTY......................................... 18
Manufactured By
A.A.C.
A Lennox International Inc. Company
421 Monroe Street
Bellevue, OH 44811
WARNING
Sharp metal edges can cause injury. When
installing the unit, use care to avoid sharp
edges.
*48283B006*
Save these instructions for future reference
# 48283B006
Page 1
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.
Slab Mounting
Discharge Air
Building
Structure
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 to the low voltage pigtails. A complete unit
wiring diagram is located inside the unit control box
cover (see also pages 16 and 17 of this instruction).
Mounting Slab
Ground Level
3. Install room thermostat on an inside wall that is not
subject to drafts, direct sunshine, or other heat sources.
2° or 2" per 5' slope tolerance away from building
structure.
4. Install low voltage wiring from outdoor to indoor unit and
from thermostat to indoor unit (see Figure 4).
Figure 2
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 field-installed low and high voltage circuits.
Wind Barrier Construction
Prevailing Winter Winds
Thermostat Designations
Wind Barrier
Inlet Air
24"
Thermostat
Indoor Unit
Power
Heat
Outdoor
Unit
R
R
W
Y
W1
Inlet Air
Cooling
Y1 Outdoor Unit
Y
Indoor Blower
G
C
G
C
C Outdoor Unit
Inlet Air
Figure 3
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.
Electrical Wiring
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.
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.
WARNING
Figure 4
Unit must be grounded in accordance with
national and local codes. Failure to ground unit
properly can result in personal injury or death.
Refrigerant Piping
Field refrigerant piping consists of liquid and suction lines
from the outdoor unit (sweat connections) to the indoor
coil (flare or sweat connections).
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.
Select line set diameters from Table 2 on page 4 to
ensure that oil returns to the compressor. Size vertical
# 48283B006
Page 3
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 at
(419) 483-4840.
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-efficiency outdoor unit:
Table 2 shows the diameters for line sets up to 100'
although vertical lift applications and trapping require-
ments need to be reviewed with Technical Services for
line sets over 50'.
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 5 shows how to place the
outdoor unit and line set to reduce line set vibration.
Refrigerant Line Set Diameters (in.)
Liquid Line
Line Set Length and Size
BTUH
12 ft. 25 ft. 50 ft. 75 ft. 100 ft.
Outside Unit Placement
and Installation
18,000 3/8
24,000 3/8
30,000 3/8
36,000 3/8
42,000 3/8
48,000 3/8
60,000 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
3/8
3/8
3/8
3/8
3/8
1/2
1/2
1/2
3/8
3/8
1/2
1/2
1/2
1/2
1/2
Install unit away
from windows
Suction Line
Line Set Length and Size
12 ft. 25 ft. 50 ft. 75 ft. 100 ft.
BTUH
Two 90° elbows installed in lineset
will reduce lineset vibration
18,000 3/4
24,000 3/4
30,000 3/4
36,000 7/8
42,000 7/8
48,000 7/8
3/4
3/4
3/4
7/8
7/8
7/8
3/4
3/4
3/4
7/8
7/8
7/8
3/4
3/4
7/8
7/8
3/4
7/8
Figure 5
7/8
Line Set Isolation
1-1/8
1-1/8 1-1/8
1-1/8 1-1/8
Illustrations on the following pages demonstrate proce-
dures 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 8 on page 6 shows how to install line
sets on vertical runs.
60,000 1-1/8 1-1/8 1-1/8 1-1/8 1-1/8
For installations exceeding 50', contact
Technical Services at (419) 483-4840.
Brazing Connection Procedure
Table 2
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.
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
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.
Page 4
# 48283B006
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 8’ intervals then strap the liquid line
to the vapor line.
Metal Sleeve
Floor Joist or Roof Rafter
Tape or Wire Tie
Figure 6
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
# 48283B006
Page 5
Refrigerant Line Sets: Installing Vertical Runs (new construction shown)
IMPORTANT: Refrigerant
lines must not contact wall.
Outside Wall
Vapor Line
Liquid Line
NOTE: Similar installation practices
should be used if line set is to be
installed on exterior of outside wall.
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
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 HCFC-22 refrigerant.
Refrigerant Metering Device
2SCU13 units are designed for use with either fixed orifice
or TXV systems. Refer to the appropriate following section
for information on installing the chosen refrigerant meter-
ing device.
4. Remove the Schrader core assemblies before brazing
to protect them from damage due to extreme heat.
Replace the cores when brazing is complete.
Fixed Orifice Systems
5. Wrap a wet cloth around the valve body and copper tube
stub to protect them from heat damage during brazing.
2SCU13 units are shipped with a fixed orifice refrigerant
metering device. Replace the existing indoor unit fixed
orifice with the orifice supplied with this unit. Place the
supplied fixed orifice sticker on the indoor cabinet after
installation. See Table 3 for the proper fixed orifice size for
each unit. In nonstandard applications, the provided fixed
orifice may not be appropriately sized.
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.
Install the fixed orifice as shown in Figure 9. Do not twist cap
tubes when loosening the seal nut from the orifice housing.
Use wrench to back up the distributor.
7. Install the factory-supplied fixed orifice (or thermal
expansion valve which is sold separately and which is
approved for use with HCFC-22 refrigerant) in the
liquid line at the indoor coil.
Expansion Valve Systems
Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. See Table 4 for proper
TXV for each unit.
Page 6
# 48283B006
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.
Fixed Orifice Data
Part
Number
Drill
Size
Model
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.
2SCU13-18
2SCU13-24
2SCU13-30
2SCU13-36
2SCU13-42
2SCU13-48
2SCU13-60
100484-07
100484-12
100484-19
100484-24
100484-30
100484-38
100484-45
.053
.062
.070
.076
.082
.091
.099
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 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.
Table 3
Manifold Gauge Set
Metering Device Installation
When checking the unit charge, use a manifold gauge set
that is equipped with “low loss” hoses. Do not use a manifold
gauge set with anything other than a “low loss” hose.
Liquid and Suction Line Service Valves
The liquid line and suction line service valves and service
ports are used for leak testing, evacuating, charging, and
checking charge.
Each valve is equipped with a service port which has a
factory-installed Schrader valve (see Figure 10 on page 8).
A service port cap protects the Schrader valve from con-
tamination and serves as the primary leak seal.
Figure 9
To Access the Schrader Port:
1. Remove the service port cap with an adjustable wrench.
2. Connect gauge to the service port.
TXV Data
Part
Number
Model
3. When testing is completed, replace service port cap.
Tighten finger tight, then an additional 1/6 turn.
2SCU13-18, -24, -30, -36
2SCU13-42, -48
2SCU13-60
26K34
26K35
91M01
To Open Liquid or Suction Line Service Valve:
1. Remove stem cap with an adjustable wrench.
2. Use a 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.
Table 4
To install an expansion valve (see Figure 9):
1. Separate the distributor assembly and remove the
piston orifice and used teflon seal. Insert nozzle end of
3. Replace the stem cap. Tighten finger tight, then
tighten an additional 1/6 turn.
# 48283B006
Page 7
Ball Type Service Valve
(Valve Open)
Service Valve
Valve Closed
Use adjustable wrench. To open, rotate stem
counterclockwise 1/4 turn (90°). To close, rotate
stem clockwise 1/4 turn (90°).
Figure 11
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.
Valve Open
WARNING
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.
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 firmly.
WARNING
3. Replace the stem cap. Tighten finger tight, then
tighten an additional 1/6 turn.
Never use oxygen to pressurize refrigeration
or air conditioning systems. Oxygen will ex-
plode on contact with oil and could cause
personal injury or death.
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 construc-
tion (see Figure 11).
Using an Electronic Leak Detector
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.
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.)
Page 8
# 48283B006
2. With both manifold valves closed, connect the cylin-
der of HCFC-22 refrigerant. Open the valve on the
HCFC-22 cylinder (vapor only).
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.
3. Open the high pressure side of the manifold to allow
HCFC-22 into the line set and indoor unit. Weigh in a
trace amount of HCFC-22. (A trace amount is a
maximum of 2 oz. of refrigerant or 3 lbs. pressure.)
Close the valve on the HCFC-22 cylinder and the
valve on the high pressure side of the manifold gauge
set. Disconnect the HCFC-22 cylinder.
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.
4. Connect a cylinder of nitrogen with a pressure regulat-
ing 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.
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.
5. Adjust nitrogen pressure to 150 psig. Open the valve
on the high side of the manifold gauge set to pressur-
ize the line set and the indoor coil.
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
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.
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.
WARNING
Do not use a compressor to evacuate a sys-
tem. 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.
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.
# 48283B006
Page 9
If the system is void of refrigerant, clean the system using
the procedure described below.
START-UP
CAUTION
1. Use dry nitrogen to pressurize the system and check
for leaks. Repair leaks, if possible.
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.
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.
1. Rotate fan to check for frozen bearings or binding.
2. Inspect all factory and field-installed wiring for loose
connections.
5. Weigh the appropriate amount of HCFC-22 refrigerant
(listed on unit nameplate) into the system.
3. After evacuation is complete, open liquid line and
suction line service valves to release refrigerant
charge (contained in outdoor unit) into 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 within 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.
4. Replace the stem caps and secure finger 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.
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 deter-
mined by the unit’s refrigerant metering device and the
outdoor ambient temperature.
6. Set thermostat for cooling demand, turn on power to
indoor blower and close the outdoor unit disconnect
switch to start the unit.
Measure the liquid line temperature and the outdoor
ambient temperature as outlined below:
7. Recheck unit voltage with unit running. Power must be
within range shown on unit nameplate.
1. Connect the manifold gauge set to the service valve
ports as follows:
Refrigerant Charging
•
•
Low pressure gauge to suction line service valve
High pressure gauge to liquid line service valve
Units are factory charged with the amount of HCFC-22
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.
2. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of HCFC-22.
3. If room temperature is below 70°F, set the room thermo-
stat to call for heat. This will create the necessary load
for properly charging the system in the cooling cycle.
Refrigerant Charge Adjustment
4. Use a digital thermometer to record the outdoor
ambient temperature.
Liquid Line Set
Diameter
Oz. per 5 ft. adjust
from 15 ft. line set*
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.
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.
6. The outdoor temperature will determine which charg-
ing method to use. Proceed with the appropriate
charging method.
Table 5
Page 10
# 48283B006
Charge Using Weigh-In Method (Fixed Orifice/TXV
Systems)
Subcooling Values for
Fixed Orifice or TXV Systems
If the system is void of refrigerant, or if the outdoor ambient
temperature is cool, first locate and repair any leaks then
use the weigh-in method to charge the unit.
Outdoor
Liquid Subcooling ( 1°F)
Temp.
°F
1. Recover the refrigerant from the unit.
-18 -24 -30 -36 -42 -48 -60
65
75
13 13
10 11
7
5
5
4
3
2
14 15
13 13
11 11
9
9
9
9
9
8
13
12
11
10
9
2. Conduct a leak check, then evacuate as previously
outlined.
85
8
7
6
3
10
10
9
3. Weigh in the charge according to the total amount
shown on the unit nameplate.
95
9
8
6
9
7
5
105
115
If weighing facilities are not available or if unit is being
charged during warm weather, follow one of the other
procedures outlined below.
6
8
Charge Using Subcooling Method (Fixed Orifice/TXV
Systems) – Outdoor Temperatures 65°F or Above
Table 6
3. Use a temperature/pressure chart for HCFC-22 to
determine the saturation temperature for the suction
line pressure reading.
If charging a fixed orifice or TXV system when the outdoor
ambient temperature is 65°F or above, the subcooling
method can be used to charge the unit.
4. Subtract the saturation temperature (according to the
chart) from the suction line temperature to determine
the superheat.
1. With the manifold gauge hose on the liquid service
port and the unit operating stably, use a digital ther-
mometer to record the liquid line temperature.
_____ ° Suction Line Temperature °F
2. At the same time, record the liquid line pressure reading.
–
_____ ° Saturation Temperature °F
3. Use a temperature/pressure chart for HCFC-22 to
determine the saturation temperature for the liquid line
pressure reading.
=
_____ ° Superheat Value °F
5. Compare the superheat value with those shown in
Table 7 on page 12. If superheat is greater than
shown, add some refrigerant. If superheat is less than
shown, recover some refrigerant.
4. Subtract the liquid line temperature from the satura-
tion temperature (according to the chart) to determine
subcooling.
_____ ° Saturation Temperature °F
Charge Using Approach Method (TXV Systems)
– Outdoor Temperatures 65°F or Above
–
_____ ° Liquid Line Temperature °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 70°F to 80°F. Monitor
system pressures while charging.
_____ ° Subcooling Value °F
5. Compare the subcooling value with those shown in
Table 6. If subcooling is greater than shown, recover
some refrigerant. If subcooling is less than shown,
add some refrigerant.
1. Record outdoor ambient temperature using a digital
thermometer.
Charge Using Superheat Method (Fixed Orifice
Systems) – Outdoor Temperatures 65°F or Above
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 suction service
port and the unit operating stably, use a digital ther-
mometer to record the suction line temperature.
3. Compare stabilized pressures with those provided in
Table 9 on page 13. Minor variations in these pres-
sures may be expected due to differences in installa-
tions. Significant differences could mean that the
system is not properly charged or that a problem
exists with some component in the system.
2. At the same time, record the suction line pressure
reading.
# 48283B006
Page 11
Superheat Values for
Fixed Orifice Systems
(80°DB/67°WB Return Air)
Approach Values for TXV Systems
Model -18 -24 -30 -36 -42 -48 -60
Outdoor Ambient Temp.
°F
Superheat
Temp.
°F
6
10 11
9
5
5
8
°F
60
65
38
35
30
26
22
18
12
8
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.
70
75
80
Table 8
85
90
95
100
105
5
0
Table 7
Pressures higher than those listed indicate that the
system is overcharged. Pressures lower 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.
_____ ° Liquid Line Temperature °F
–
=
_____ ° Outdoor Ambient Temperature °F
_____ ° Approach Temperature °F
6. Compare the approach value with those shown in
Table 8. If the values to do not agree with those
provided in Table 8, 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 9 to perform maintenance checks. Table 9 is
not a procedure for charging the system. Minor variations
in these pressures may be due to differences in installa-
tions. Significant deviations could mean that the system is
not properly charged or that a problem exists with some
component in the system.
Page 12
# 48283B006
Normal Operating Pressures
Model
Outdoor Coil
Entering Air
Temperature
-18
-24
-30
-36
-42
-48
-60
L
S
L
S
L
S
L
S
L
S
L
S
L
S
Expansion Valve (TXV)
141 80 147 79 141 76 145 74 143 78 145 80
65°F
75°F
151 76
166 81 173 80 167 77 170 76 167 80 170 81 177 78
195 82 218 82 195 78 201 77 198 81 198 82 207 79
222 83 234 82 227 80 234 78 231 82 230 84 240 80
85°F
95°F
105°F
115°F
258 85 267 84 260
81 268 79 268 84 265 85 277
81
294 86 307 85 299 83 309 81 308 85 303 86 318 83
Fixed Orifice (RFC)
65°F
75°F
144 73 147 68 140 66 150 67 147 70 145 70 150 67
167 78 173 74 166 71 176 72
196 82 203 79 196 76 205 76 198 78 198 80 207 77
225 84 238 83 227 80 237 79 228 81 230 84 239 80
256 86 272 86 262 83 273 81 262 84 264 86 274 83
293 88 317 88 302 86 314 84 300 85 301 88 315 85
171 75 170 75 177 72
85°F
95°F
105°F
115°F
L – Liquid S – Suction
Values provided above are typical pressures. Indoor unit matchup, indoor air quality, and indoor load will cause
pressures to vary.
Table 9
# 48283B006
Page 13
OPERATION
MAINTENANCE
WARNING
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.
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 quali-
fied 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 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 evi-
dence 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 10.
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.
4. Check all wiring for loose connections.
# 48283B006
Page 14
5. Check for correct voltage at unit (with unit operating).
6. Check amp-draw on blower motor.
Unit nameplate _________ Actual _________
Start-Up and Performance Checklist
Job Name _______________________________
Job Location _____________________________
Installer _________________________________
Job No. ________________
City ___________________
City ___________________
Date ______________
State ______________
State ______________
Unit Model No.______________
Serial No. ___________________
Service Technician ________________________________________
Nameplate Voltage ______________
Outdoor Fan ___________________
Rated Load Ampacity ________
Compressor _______________
Maximum Fuse or Circuit Breaker________________________
Electrical Connections Tight?
Indoor Filter Clean?
Supply Voltage (Unit Off) ________________
Indoor Blower RPM _____________
S.P. Drop Over Indoor (Dry) ____________
Voltage with Compressor Operating _____________
Vapor Pressure ____________
Outdoor Coil Entering Air Temperature _____________
Discharge Pressure___________
Refrigerant Charge Checked?
Refrigerant Lines: Leak Checked?
Service Valves: Fully Opened?
Outdoor Fan Checked?
Properly Insulated?
Caps Tight?
Thermostat: Calibrated?
Properly Set?
Level?
# 48283B006
Page 15
OUTDOOR
FAN
DUAL
A4
CAPACITOR
TIMED OFF
CONTROL
(IF USED)
PURPLE
BLACK
C
F
H
TO 24 VAC
POWER SOURCE
20 VA MINIMUM
NEC CLASS 2
ORANGE
3
2
1
RED
YELLOW
Y1
C
BLACK
R
S
C
COMPRESSOR
CONTACTOR
CRANKCASE HEATER
(IF USED)
COMPRESSOR
L2
L1
GROUND
LUG
208-230/60/1
GROUND
BLACK
L1
C
S
R
1
K1-1
B1
S4 HIGH
S24 LOSS
OF CHARGE
SWITCH
208-230/60/1
L2
YELLOW
RED
PRESSURE
SWITCH
(IF USED)
(IF USED)
ORANGE
BLACK
A4
S24
S4
2
3
1
HR1
K1
H
C
F
EQUIPMENT
GROUND
B4
PURPLE
C12
C
Y1
TO 24 VAC
POWER SOURCE
20 VA MINIMUM
NEC CLASS 2
FOR USE WITH COPPER CONDUCTORS ONLY. REFER TO UNIT RATING
PLATE FOR MINIMUM CIRCUIT AMPACITY AND MAXIMUM OVERCURRENT
PROTECTION SIZE.
1
WARNING--
DESCRIPTION
ELECTRIC SHOCK HAZARD, CAN CAUSE INJURY OR DEATH.
UNIT MUST BE GROUNDED IN ACCORDANCE WITH NATIONAL
AND LOCAL CODES.
KEY
A4
B1
COMPONENT
CONTROL - TIMED OFF
COMPRESSOR
B4
MOTOR - OUTDOOR FAN
CAPACITOR - DUAL
HEATER - COMPRESSOR
CONTACTOR - COMPRESSOR
SWITCH - HIGH PRESSURE
SWITCH - LOSS OF CHARGE
LINE VOLTAGE FACTORY INSTALLED
LINE VOLTAGE FIELD INSTALLED
24 VOLT FACTORY INSTALLED
C12
HR1
K1-1
S4
CLASS II VOLTAGE FIELD INSTALLED
S24
Single Phase Wiring Diagram P/N 48352-001
Figure 12
Page 16
# 48283B006
B4
OUTDOOR
FAN
C1
OUTDOOR FAN
CAPACITOR
A4
TIMED OFF
CONTROL
(IF USED)
PURPLE
BLACK
TO 24 VAC
POWER SOURCE
10 VA MINIMUM
NEC CLASS 2
ORANGE
BLACK
2
3
1
C
Y1
BLACK
COMPRESSOR
B1
BLACK
T2
T3
L3
T1
COMPRESSOR
CONTACTOR
K1
CRANKCASE HEATER
(IF USED)
L2 L1
1
L1
HR1
L2
L3
GROUND
208-230/60/3
LUG
GROUND
208-230/60/3
L1
S40
K1-1
BLACK
2
B1
1
BLACK
BLACK
L2
L3
S4 HIGH
PRESSURE
SWITCH
S24 LOSS
OF CHARGE
SWITCH
(IF USED)
(IF USED)
ORANGE
A4
S24
EQUIPMENT
GROUND
S4
2
3
1
HR1
C1
K1
PURPLE
S40
B4
C
Y1
TO 24 VAC
POWER SOURCE
10 VA MINIMUM
NEC CLASS 2
FOR USE WITH COPPER CONDUCTORS ONLY. REFER TO UNIT RATING
PLATE FOR MINIMUM CIRCUIT AMPACITY AND MAXIMUM OVERCURRENT
PROTECTION SIZE.
1
2
DESCRIPTION
COMPONENT
JUMPER IS USED WHEN TOC IS NOT USED.
KEY
A4
B1
B4
CONTROL - TIMED OFF
COMPRESSOR
WARNING--
ELECTRIC SHOCK HAZARD, CAN CAUSE INJURY
OR DEATH. UNIT MUST BE GROUNDED IN
ACCORDANCE WITH NATIONAL AND LOCAL CODES.
MOTOR - OUTDOOR FAN
CAPACITOR - OUTDOOR FAN
HEATER - COMPRESSOR
CONTACTOR - COMPRESSOR
SWITCH - HIGH PRESSURE
SWITCH - LOSS OF CHARGE
THERMOSTAT - CRANKCASE
C1
HR1
K1-1
S4
S24
S40
LINE VOLTAGE FACTORY INSTALLED
LINE VOLTAGE FIELD INSTALLED
24 VOLT FACTORY INSTALLED
CLASS II VOLTAGE FIELD INSTALLED
Three Phase Wiring Diagram P/N 48436-001
Figure 13
# 48283B006
Page 17
Limited Warranty
August 1, 1997
This warranty gives you specific legal rights and you may have other rights
which vary from state/province to state/province.
Warrantor: Armstrong Air Conditioning Inc., 421 Monroe St., Bellevue, OH 44811
Armstrong Air Conditioning Inc. products are available under the following names: Air Ease, Armstrong Air, American Aire, Concord
Subject to the limitations stated in this warranty, we warrant to the first buyer for use the residential heating, cooling or heat pump unit, when
installed, operated and maintained as required by this warranty, to be free of defects in workmanship or material for a period of 5 years
(1 year for commercial equipment) from the time of installation. We will replace any defective component without cost or expense to you
except for the costs of delivery and labor for removal and replacement of the defective component.
The 2SCU13LB Series air conditioners carry a 5-year compressor warranty. The 2SCU13LE Series air conditioners carry a 10-year
compressor warranty.
Warranty Begins
The warranty period begins when the installation is complete and the product is ready to operate. You must be able to verify this date
whenever a warranty claim is made. Original bill of sale, installer’s invoice or other similar document will suffice. If the beginning date
cannot be verified, we will consider warranty coverage to begin 6 months after the date the product was shipped from our factory.
Limitations on Implied Warranties
Implied warranties of merchantability or, to the extent applicable, fitness for a particular purpose are limited to 5 years, the same duration
as the basic limited written warranty provided herein. Some states/provinces do not allow limitations on how long an implied warranty of
merchantability or fitness lasts, so the above limitations or exclusions may not apply to you.
Only Warranty
This written Limited Warranty is the only warranty made by the warrantor; this warranty is in lieu of and excludes all other warranties,
express or implied. The warrantor does not authorize any person to provide any other warranty or to assume for it any further obligation in
connection with the warranted product.
What is NOT Covered
1. Cabinets or cabinet pieces.
2. Normal maintenance items such as filters, fan belts, fuses or other consumable items.
3. Damage caused by misuse, failure to maintain properly, accidents or acts of God.
4. External wiring, piping, venting or attachment of accessory products not integral to our product, including without limitation,
humidifier, air cleaner, vent damper, thermostat or other mechanical devices not manufactured by the warrantor.
5. Products that have been operated in a corrosive atmosphere where a concentration of acids, halogenated hydrocarbons or
other corrosive elements causes deterioration to metal surfaces or integral components. NOTE: Operation in a corrosive
atmosphere is considered abuse and voids this warranty.
6. Products that have NOT been installed in accordance with our published installation instructions, applicable local, state/
provincial or national codes, ACCA published standards.
7. Products that have NOT been installed by competent, qualified installers.
8. Products that have been moved from their original place of installation.
Warranty on Replacement Components
Any replacement component furnished by us will assume the remaining (unused) portion of the Limited Warranty.
Consequential Damages
The warrantor shall not be responsible for any consequential damages caused by any defect in the product. Some state/provinces do not
allow the exclusion or limitations of incidental or consequential damages, so the above limitation or exclusion may not apply to you.
This product must be installed, used and cared for in accordance with the instruction manual. You are responsible for required periodic
maintenance or service, such as changing or cleaning of air filters and lubrication or cleaning of components. Failure to properly install,
operate or maintain your unit voids this warranty.
Page 18
# 48283B006
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