9
12.1 Low Voltage Connections
Several combinations of low voltage schemes are possible,
depending on the presence of a heat kit and whether the
heat kit is single-stage or multi-stage, whether the outdoor
section is an air conditioner or heat pump, and whether
the outdoor section is single-stage or two stage. The
24V-control voltage connects the air handle to the room
thermostat and condenser. Low voltage wiring must be
copper conductors. A minimum of 18AWG must be used
for installations. Low voltage wiring must be connected
through the top of the cabinet or either side.
0.1
0.2
0.3
T1
630
602
576
T2
630
602
576
T3
637
609
586
T4
630
602
576
T5
846
824
800
T1
630
602
576
T2
630
602
576
T3
784
763
742
T4
630
602
576
T5
846
823
800
T1
683
604
525
T2
900
856
803
T3
1079
1025
989
T4
944
897
848
T5
1168
1127
1083
T1
1114
1072
1031
T2
1114
1072
1031
T3
1225
1191
1152
T4
1287
1255
1219
T5
1360
1329
1299
Model
Speed
Tap
CFM @ STATIC PRESSURE (IN W.C.)
AWSF18SU16** AA
AWST18SU14** AA
AWSF24SU16** AA
AWST24SU14** AA
AWSF30LU16** AA
AWST30LU14** AA
AWSF36LU16** AA
AWST36LU14** AA
Table 4
NOTE:
1.
Airflow data indicated is at 230V without air filter in
place.
2. Select a speed tap that provides a minimum 300 CFM
per outdoor ton. For satisfactory operation, external
static pressure must no exceed 0.3" WC (for electric
heater only).
13 EXPANSION VALVE TROUBLESHOOTING
Before replacing an expansion valve, check the following
items:
1. Bulb location: Must be tightly secured to the suction
line upstream of the equalizer connection.
2. Insulation: Bulb must be properly insulated.
3. Equalizer: Must be connected to the 1/4” SAE
connection on the suction line.
4. Charge: Ensure the system is properly charged. There
MUST be a minimum of 10°F Sub-Cooled liquid at the
valve inlet.
If the system appears to be “starving” (low suction pressure
but insufficient cooling):
1. Check the Superheat (SH) at the evaporator outlet.
If SH is between 5°F - 12°F, the TXV is controlling
properly.
- Verify that there is proper airflow to the evaporator
(fan is operating and filter is unrestricted).
2. If SH is above 12°F, the setting of the TXV may be too
high.
- Adjust the SH by turning counter-clockwise to
decrease SH.
- Wait 20 minutes for the system to balance and adjust
again, as required.
- If adjusting the valve has no effect on the SH, the
valve may be stuck because of dirt or debris or it may
have lost the Power Element charge.
3. After properly reclaiming the refrigerant, remove the
TXV and check for dirt and debris. Clean, if possible, or
replace the TXV and filter/drier.
If the system appears to be “flooding” (compressor frosting
or moisture is condensing at the suction connection):
1. Check the SH at the evaporator outlet. If SH is
between 5°F - 12°F, the TXV is controlling properly.
2. If SH is less than 5°F, the SH adjustment may be too
low.
- Adjust the SH by turning the adjustment stem clock-
wise to increase the SH.
- Wait 20 minutes for the system to balance and ad-
just again as required.
- If adjusting the valve has no effect on the SH, the
valve may be stuck open because of dirt or debris or
moisture in the refrigerant.
3. After properly reclaiming the refrigerant, remove the
TXV and check for dirt and debris. Clean, if possible,
or replace the TXV and filter/drier. Add a moisture
indicator to allow checking of moisture if this is believed
to be a probable cause.
