Symptom | Possible Cause | Remedy |
| Power off or loose electrical connection | Make sure main switch is ON. Check and tighten all connections. |
| Incorrect thermostat setting | Set thermostat correctly |
No cooling | Defective contactor | Check for 24V at contactor coil. |
| Open circuit breaker of blown fuses | Reset or replace |
| Defective transformer | Check wiring - Replace it. |
| Interconnecting low voltage wiring damage | Replace thermostat wiring |
| Dirty filters | Clean & replace |
| Indoor air blockage | Check supply registers and return grills for blockage. |
| Blocked outdoor coil | Clear away leaves and other debris |
| Improperly sized unit | Recalculate load |
Insufficient Cooling | Improper airflow | Check - should be 400CFM/Ton |
| Incorrect refrigerant charge | Charge correctly per instruction. |
| Air, | Recover refrigerant, evacuate & recharge, add filter drier |
| Incorrect voltage | At compressor terminals, voltage must be within |
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| 10% of rating plate volts when unit is running. |
Water on floor or in |
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furnace | Blocked condensate drain and "P" trap | Remove blockage |
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| Run or start capacitor defective | Replace |
| Loose connection | Check and tighten all connections. |
Condenser fan runs, | Compressor stuck, grounded or open | Wait for 2 hours for overload to reset. |
compressor doesn't | motor winding, open internal overload | Replace compressor if still open. |
| Low voltage condition | At compressor terminals, voltage must be within 10% of rating |
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| plate volts when unit is running. |
| Low voltage condition | Add start kit components |
| Incorrect voltage | At compressor terminals, voltage must be within 10% of rating |
Compressor |
| plate volts when unit is running. |
Defective overload protector | Replace - check for correct voltage | |
| Refrigerant undercharge | Add refrigerant |
Register sweat | Low evaporator airflow | Increase blower speed or reduce restriction - replace air filter |
| Restriction in liquid line, | Replace defective components |
High head - Low | metering device or filter drier |
|
vapor pressures | Flowrator piston size too small | Change to correct size piston |
| Incorrect capillary tubes | Change coil assembly |
| Blocked outdoor coil | Clear away leaves and other debris |
High head - High | Refrigerant overcharge | Correct system charge |
or normal vapor | Condenser fan not running | Repair or replace |
pressures | Air, | Recover refrigerant, evacuate & |
| moisture in system | recharge, add filter drier |
Low head - High | Flowrator piston size too large | Change to correct size piston |
vapor pressures | Defective compressor valves | Replace compressor |
| Incorrect capillary tubes | Replace coil assembly |
Low vapor - cool | Low evaporator airflow | Increase blower speed or reduce restriction - replace air filter |
compressor - iced | Operating below 65 F outdoors | Add low ambient kit |
evaporator coil | Moisture in the system | Recover refrigerant, evacuate & recharge, add filter drier |
High vapor | Excessive load | Recheck load calculation |
pressure | Defective compressor | Replace |
Fluctuating head | Air or | Recover refrigerant, evacuate & recharge. |
and vapor pressures |
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Pulsing noise at | Air or | Recover refrigerant, evacuate & recharge |
metering device |
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or liquid line |
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