Unit Won't Start Normally
Manually push in main contactor for a few seconds
- If Compressor Starts
- Problem is either in the Low Voltage Control or safety circuits or the contactor itself
- Check the following:
- High Pressure Control
- Low Pressure Control
- Internal/External Overload
- Transformer
- Thermostat
- Furnace Fuse
- 24V Wiring to Condenser (maybe a dog or landscaper is involved)
- If Compressor Hums but Will Not Start
- On CSR units check the following
- Start Capacitor
- Start Relay
- Open Circuit in Compressor
- On PSC units check the following
- Run capacitor
- High head pressure
- Open Circuit in Compressor
- On CSR units check the following
- If Compressor Won't Start
- Main fuses
- Internal Overload
- Open Circuit in Compressor
- Grounded Compressor
Compressor Runs Continuously
If the unit is not cooling, check the following:
- Refrigerant charge low
- Evaporator fins dirty
- Compressor valves bad
- Ductwork too small
- Air filter dirty
- Furnace blower not delivering enough air
- Thermostat - Stuck
- Thermostat - Location
- Knee deep cooling - Air supply and return grills may both be low causing stratification of cool air at floor level - Relocate return air.
Compressor Short-Cycles
Check the following:
- Low pressure
- External overload
- High Pressure
- Run cap bad
- Internal overload
Head Pressure Checks
If high, check the following:
- Refrigerant overcharge
- Air in refrigerant (CRUD)
- Plugged fins on condenser coil
- Condenser fan not operating
- Low refrigerant charge
- Low suction pressure
- Low condenser air temperature
Suction Pressure Checks
If high, check the following:
- Bad compressor valves
- Low head pressure
- Excessive load
- Low refrigerant charge
- Dirty air filter
- Evaporator fins dirty
- Ductwork too small
- Blower not delivering enough air
- Plugged refrigerant line - kinked
- Plugged refrigerant dryer