Carrier Aquazone 50PTH036 Installation, Start-Up And Service Instructions Manual page 33

FAULT
Entire unit does not run
Blower operates but compressor
does not
Unit off on high pressure control Discharge pressure too high
Unit off on low pressure control
Unit short cycles
Insufficient cooling or heating
Table 15 — Troubleshooting
POSSIBLE CAUSE
Power Supply Off
Blown Fuse
Voltage Supply Low
Thermostat
Thermostat
Wiring
Safety Controls
Compressor overload open
Compressor motor grounded
Compressor windings open
Refrigerant charge
High pressure
Suction pressure too low
Refrigerant charge
Low pressure switch
Unit oversized
Thermostat
Wiring and controls
Unit undersized
Loss of conditioned air by leakage
Airflow
Refrigerant charge
Compressor
Reversing Valve
Operating pressures
TXV
Moisture, noncondensables
Apply power, close disconnect.
Replace fuse or reset circuit breaker. Check for correct fuses.
If voltage is below minimum voltage specified on unit data plate, contact local power com-
pany.
Set the fan to ON, the fan should run. Set thermostat to COOL and lowest temperature set-
ting, the unit should run in the cooling mode (reversing valve energized). Set unit to HEAT
and the highest temperature setting, the unit should run in the heating mode (reversing valve
deenergized).
If neither the blower or compressor run in all three cases, the thermostat could be miswired or
faulty. To ensure miswired or faulty thermostat verify that 24 volts is available at the low volt-
age terminal strip between "R" and "C", "Y" and "C", and "O" and "C". If the blower does not
operate, verify 24 volts between terminals "G" and "C". Replace the thermostat if defective.
Check setting, calibration, and wiring.
Check for loose or broken wires at compressor, capacitor, or contactor.
Check Complete C board red default LED for blink code.
If the compressor is cool and the overload will not reset, replace compressor.
Internal winding grounded to the compressor shell. Replace compressor.
After compressor has cooled, check continuity of the compressor windings. If the windings
are open, replace the compressor.
In "COOLING" mode: Lack of or inadequate water flow. Entering water temperature is too
warm. Scaled or plugged condenser. In "HEATING" mode: Lack of or inadequate airflow.
Blower inoperative, clogged filter or restrictions in ductwork
The unit is overcharged with refrigerant. Recover refrigerant, evacuate and recharge with fac-
tor recommended charge.
Check for defective or improperly calibrated high pressure switch.
In "COOLING" mode: Lack of or inadequate airflow. Entering air temperature is too cold.
Blower inoperative, clogged filter or restrictions in ductwork
In "HEATING" mode: Lack of or inadequate water flow. Entering water temperature is too
cold. Scaled or plugged condenser.
The unit is low on refrigerant. Check for refrigerant leak, repair, evacuate and recharge with
factory recommended charge.
Check for defective or improperly calibrated low pressure switch.
Recalculate heating and or cooling loads.
Thermostat installed near a supply air grille; relocate thermostat. Readjust heat anticipator.
Check for defective or improperly calibrated low pressure switch.
Recalculate heating and or cooling loads. If excessive, possibly adding insulation and shad-
ing will rectify the problem.
Check for leaks in ductwork or introduction of ambient air through doors or windows.
Lack of adequate airflow or improper distribution of air. Replace dirty filter.
Low on refrigerant charge causing inefficient operation.
Check for defective compressor. If discharge is too low and suction pressure is too high, com-
pressor is not pumping properly. Replace compressor.
Defective reversing valve creating bypass of refrigerant from discharge of suction side of
compressor. Replace reversing valve.
Compare unit operation pressures to the pressure/temperature chart for the unit.
Check TXV for possible restriction or defect. Replace if necessary.
The refrigerant system may be contaminated with moisture or noncondensables. Recover
refrigerant, replace filter dryer, evacuate the refrigerant system, and recharge with factory
recommended charge.
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SOLUTION