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TROUBLESHOOTING
PROBLEM SOLUTION
COMPRESSOR DOES NOT RUN
Contactor Open
1. Power off. 1. Restore power.
2. Fuses blown in field power circuit. 2. After finding cause and correcting, replace with correct size fuse.
3. No control power. 3. Check secondary fuse(s); replace with correct type and size.
Replace transformer if primary windings receiving power.
4. Thermostat circuit open. 4. Check thermostat setting.
5. Time Guardா II device not operating. 5. Check Time Guard II devices.
6. Compressor circuit breaker tripped. 6. Check for excessive compressor current draw. Reset breaker;
replace if defective.
7. Safety device lock-out circuit active. 7. Reset lock-out circuit at thermostat or circuit breaker.
8. Low-pressure switch open. 8. Check for refrigerant undercharge, obstruction of indoor airflow, or
whether compressor suction shutoff valve is fully open. Make sure liquid
line solenoid valve(s) is open.
9. High-pressure switch open. 9. Check for refrigerant overcharge, obstruction of outdoor airflow, air in
system, or whether compressor discharge valve is fully open. Be sure
outdoor fans are operating correctly.
10. Compressor overtemperature switch open. 10. Check for open condition. Allow for reset. Replace if defective.
11. Loose electrical connections. 11. Tighten all connections.
12. Compressor stuck. 12. See compressor service literature.
Contactor Closed
1. Compressor leads loose. 1. Check connections.
2. Motor windings open. 2. See compressor service literature.
3. Single phasing. 3. Check for blown fuse. Check for loose connection at compressor terminal.
COMPRESSOR STOPS ON HIGH-PRESSURE SWITCH
Outdoor Fan On
1. High-pressure switch faulty. 1. Replace switch.
2. Reversed fan rotation. 2. Confirm rotation, correct if necessary.
3. Airflow restricted. 3. Remove obstruction.
4. Air recirculating. 4. Clear airflow area.
5. Noncondensables in system. 5. Purge and recharge as required.
6. Refrigerant overcharge. 6. Purge as required.
7. Line voltage incorrect. 7. Consult power company.
8. Refrigerant system restrictions. 8. Check or replace filter drier, expansion valve, etc. Check that compressor
discharge service valve is fully open.
Outdoor Fan Off
1. Fan slips on shaft. 1. Tighten fan hub setscrews.
2. Motor not running. 2. Check power and capacitor.
3. Motor bearings stuck. 3. Replace bearings.
4. Motor overload open. 4. Check overload rating. Check for fan blade obstruction.
5. Motor burned out. 5. Replace motor.
COMPRESSOR CYCLES ON LOW-PRESSURE SWITCH
Indoor-Air Fan Running
1. Compressor suction service valve partially
closed.
1. Open valve fully.
2. Liquid line solenoid valve(s) fails to open. 2. Check liquid line solenoid valve(s) for proper operation. Replace if
necessary.
3. Filter drier plugged. 3. Replace filter drier.
4. Expansion valve power head defective. 4. Replace power head.
5. Low refrigerant charge. 5. Add charge. Check low-pressure switch setting.
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