32
Marvair Classic AVPA/HVPA/HVPSA Heat Pump I&O Manual
11/2017 Rev. 7
PROBLEM/SYMPTOM
LIKELY CAUSE(S)
CORRECTION
C. Unit cycles on high pressure or
loss of charge.
1. Loss or restriction of airflow.
2. Restriction in refrigerant circuit.
3. Refrigerant overcharge (following
field service)
4. Defective high pressure control or
loss of charge switch.
1. Check blower assembly for proper opera-
tion. Look for airflow restrictions, e.g., the air
filter. Check blower motor and condenser fan.
Indoor blower fan speed control set too low.
2. Check for blockage or restriction, especially
filter drier and capillary tube assembly.
3. Evacuate and recharge to factory
specifications.
4. Check limit cutout pressures. Control is set to actu-
ate at approximately 40 PSIG (loss of charge)
and 610 PSIG (high pressure).
D. Unit blows fuses or trips circuit
breaker.
1. Inadequate circuit ampacity.
2. Short, loose, or improper connection
in field wiring.
3. Internal short circuit. Loose or
improper connection(s) in unit.
4. Excessively high or low supply volt-
age or phase loss (3ø only).
1. Note electrical requirements in Chapter 2 and
correct as necessary.
2. Check field wiring for errors.
3. Check wiring in unit. See wiring and sche-
matic diagrams. Test components (especially
the compressor) for shorts.
4. Note voltage range limitations specific to the
compressor troubleshooting section.
E. Water on floor near unit.
1. Obstruction in condensate line.
2. Obstruction or leak in condensate
pan.
3. Unit is not level.
1. Check for clog or restriction.
2. Check pan for leak or blockage.
3. Level unit.
F. No space heating or reduced heat-
ing (units equipped with resistance
elements)
1. Defective heating element(s).
2. Thermal limit open.
3. Defective heater contactor.
4. Thermostat set too low.
5. Compressor fault.
1. Check resistance element(s) for continuity.
2. Check continuity across thermal limit switch.
3. Check relay for proper operation. Replace if
defective.
4. Adjust thermostat.
5. Reset the lock out relay at the thermostat.
4.3 Compressor Troubleshooting
Obtain the heat pump's model number and serial number, the compressor's model number and contact
Airxcel Commercial Group for compressor specifications.
It is important to rule out other component failures before condemning the compressor.
The following electrical tests will aid diagnosis on single phase "HPA" units:
1.
Start-Up Voltage:
Measure the voltage at the compressor contactor during start-up. The voltage must
exceed the minimum shown in Table 8, section 2.2, or compressor failure is likely. A low voltage
condition must be corrected.
