Heat Pump Troubleshooting Guide: Diagnose Common Problems

Heat pump troubleshooting can help you identify common issues before calling a technician. While many problems require professional heat pump repair, some can be resolved with simple steps that save you the cost of a service call.

Heat Pump Troubleshooting: Quick Checks First

Before diving into specific problems, run through these basic heat pump troubleshooting checks:

1. Thermostat settings — Verify the thermostat is set to the correct mode (heat or cool) and the temperature is set appropriately
2. Power supply — Check that the circuit breaker has not tripped and the disconnect switch near the outdoor unit is in the ON position
3. Air filter — A dirty filter is the most common cause of heat pump problems. Check and replace if needed
4. Outdoor unit — Ensure the outdoor unit is not blocked by snow, ice, leaves, or debris

Problem: Heat Pump Not Turning On

Troubleshooting Steps

1. Check the thermostat and replace batteries if it is blank
2. Verify the circuit breakers for both indoor and outdoor units
3. Check the outdoor disconnect switch
4. Look for error codes on the thermostat or indoor unit
5. Reset the system by turning it off for 5 minutes, then back on

When to call a pro: If the system still will not turn on after these steps, you likely have an electrical issue, a failed contactor, or a bad compressor that requires professional diagnosis.

Problem: Heat Pump Not Heating

Troubleshooting Steps

1. Confirm the thermostat is set to HEAT mode
2. Check the air filter and replace if dirty
3. Verify the outdoor unit is running
4. Check if the outdoor unit is covered in ice (defrost issue)
5. Make sure all supply registers are open

When to call a pro: If the outdoor unit is running but only cold air comes from the vents, you may have a reversing valve problem, refrigerant leak, or compressor issue.

Problem: Heat Pump Freezing Up

Troubleshooting Steps

1. Check the air filter and replace if dirty
2. Verify all supply and return vents are open and unblocked
3. Listen for the defrost cycle engaging (you will hear the reversing valve click)
4. Check outdoor airflow and clear any debris around the unit

When to call a pro: If the unit remains frozen after clearing debris and changing the filter, the defrost control board, sensor, or reversing valve likely needs repair.

Problem: Heat Pump Making Noises

Noise Type	Likely Cause	DIY or Pro?
Grinding	Worn motor bearings	Call a pro
Squealing	Belt or bearing issue	Call a pro
Rattling	Loose panels or debris	Check for loose screws/debris first
Clicking (repeated)	Electrical relay issue	Call a pro
Hissing	Refrigerant leak	Call a pro immediately
Whooshing	Normal defrost cycle	Normal operation

Problem: High Energy Bills

Troubleshooting Steps

1. Check if the system is running on auxiliary/emergency heat (the AUX light on your thermostat). This electric resistance heat costs 2-3 times more than heat pump mode
2. Replace the air filter
3. Verify the thermostat is not set too high (above 72 degrees in winter)
4. Check for drafts around windows and doors
5. Inspect ductwork for visible leaks

When to call a pro: If the AUX heat runs constantly or the system cannot maintain temperature without it, the heat pump may need a refrigerant charge, compressor repair, or other professional service.

Heat Pump Troubleshooting by Brand

Different brands have different error code systems and common failure points. For brand-specific heat pump troubleshooting, see our guides for Carrier, Trane, Lennox, Goodman, and Rheem.

If your heat pump troubleshooting reveals a problem that requires professional attention, get a cost estimate and connect with a certified technician through our repair service.

Related Heat Pump Services

• Heat Pump Repair Services
• Heat Pump Installation Guide
• Preventive Maintenance Plans
• Heat Pump Repair Cost Guide
• Emergency Heat Pump Repair

Our technicians are certified under EPA Section 608 and follow best practices recommended by the U.S. Department of Energy for heat pump troubleshooting services.