How to Troubleshoot Common Heat Pump Compressor Problems

  • 1-2 hours
  • Beginner
  • 25-250
What You'll Need
Voltage meter with ohms readout
Air filters
What You'll Need
Voltage meter with ohms readout
Air filters

Common heat pump compressor problems can often be diagnosed by the homeowner, without the need to call a costly service repair technician.

Going through these simple steps may save you time, money, and hassle, and help you decide whether it is worth it to repair your compressor, or if it would be better to replace it.

Step 1 - Check for Other Problems

Before calling a technician or attempting to replace a heat pump compressor, go through alternative, easy-to-solve problems. Check the registers for sufficient airflow, which may be blocked by dirty or worn out filters.

Replace the air filter; air filters should be replaced monthly during heavy-use seasons. Check to see if the unit is running continuously, and try lowering the thermostat level.

If lowering the temperature doesn't work, you may be low on refrigerant or have debris blocking the exterior portion of your heat pump. Make sure that your air handler is getting sufficient voltage, and that power is running properly to the line. Try switching the fan to automatic; if the blower runs, the air handler is working fine. If the handler is frozen, it may simply need to be defrosted.

Step 2 – Troubleshooting Hard Starting Motors

The 2 most common types of compressor problems are burned out motors and hard starting motors. A hard-starting motor will work with difficulty, whereas a burned out motor will not work at all. A hard starting compressor usually stutters when it is turned off or on.

The compressor may also begin to cycle on, and then shut off, only to try again a moment later. A compressor that continuously trips the circuit breaker assigned to its circuit may be burning out, and that the wiring inside the compressor may be overloading your circuit.

Alternatively, the line may not be producing enough voltage to run the compressor; unusually low voltage can cause a compressor to hard start, and eventually do damage to your heat pump.

This symptom may require an electrician to diagnose house-related wiring issues; your breaker box may be overloaded, or you may have a short in the line. Either way, it is best at this point to disconnect the heat pump until the wiring is resolved, to avoid the possibility of shorting out the motor.

Step 3 - Troubleshooting Burned Out Motors

When the motor is burned out, the wiring inside of the compressor has been damaged beyond repair, and the windings may be shorted or burned together, or come apart. This is the least desirable outcome for the compressor. A burned out compressor motor will prevent the unit from starting.

Unplug the unit and turn off all power. Using a voltage meter, measure the resistance in ohms between the motor and the terminals. If there is no resistance, the winding is no longer attached properly. If, on the other hand, the meter's needle points to infinity, the compressor is burned through. Either way, you will need to replace your heat pump.