Heat Pump Problems: What Homeowners Should Know
Heat pumps provide both heating and cooling from the same equipment, which makes their issues a little different from a separate AC or furnace. This guide walks through the most common heat pump problems homeowners run into and where to draw the line on troubleshooting.
- Heat pumps run year-round, so symptoms can show up in either heating or cooling mode.
- Ice on the outdoor unit in winter is part of normal operation — until it doesn't melt.
- Auxiliary heat running constantly often points to a deeper issue.
- Filter, thermostat, and airflow checks resolve a meaningful share of issues.
- Refrigerant and electrical work belong to a licensed HVAC contractor.
Heat pump not heating or cooling
Confirm the thermostat mode, setpoint, fan setting, and batteries. Check the air filter and make sure the outdoor unit is running and clear of debris. If the system is in heat mode but blowing cool air, check whether auxiliary heat is enabled.
Heat pump running constantly
Some long runtime is normal for heat pumps, especially in cold weather. Constant runtime with the home not reaching setpoint can indicate refrigerant issues, airflow problems, or equipment that is undersized for the conditions.
Weak airflow
Weak airflow at the registers usually points to a dirty filter, blocked return, dirty indoor coil, or ductwork issue. Check the filter first, then call a contractor if airflow stays weak.
Ice on the outdoor unit
Some frost or ice on the outdoor unit during winter operation is normal — the unit runs a defrost cycle periodically. Heavy ice that doesn't melt, ice across the entire coil, or a unit fully encased in ice usually means the defrost cycle is not working correctly.
Defrost cycle basics
During heating mode in cold weather, the heat pump periodically reverses to melt frost off the outdoor coil. You may notice steam from the outdoor unit and a brief moment of cooler air from the vents — both are normal during defrost.
Thermostat or mode setting issues
Heat pumps often have separate emergency heat, auxiliary heat, and standard heat settings. Wrong mode selection can cause heating to run inefficiently or behave unexpectedly. Confirm the thermostat is set correctly for the conditions.
When repair may make sense
If the system is newer, the issue is isolated, and the unit has been reliable, repair is usually the better choice. Common repair items include capacitors, contactors, defrost controls, and reversing valve solenoids.
When replacement may be worth discussing
Compressor failure on an older heat pump, repeated refrigerant problems, or a system that cannot keep up with comfort needs are reasons to compare replacement alongside repair.
Questions to ask before deciding
- Is the issue in heating mode, cooling mode, or both?
- Is the defrost cycle working correctly?
- Is the system properly sized for the home and climate?
- Is auxiliary or emergency heat working as expected?
- Is the refrigerant charge correct, and has it been checked?
- What repair options are available, and what would replacement look like?
When to call an HVAC contractor
- Heat pump is not heating or cooling after basic checks
- Outdoor unit is fully iced over and does not melt
- Auxiliary heat is running constantly in mild weather
- Loud or unusual noises from indoor or outdoor unit
- Repeated breaker trips or burning smell
What to have ready before requesting help
- System age and approximate install year
- What mode the system is in and what it's doing
- Recent repair history
- Photos of the equipment label and any icing
- Whether the issue is urgent (very hot or very cold conditions)
Need Help Comparing HVAC Options?
Whether you are dealing with an AC issue, furnace problem, heat pump question, or possible system replacement, HSRC can help you understand the next step and get connected with a local licensed HVAC contractor.
Availability, pricing, licensing, services, and response times may vary by location and provider.
Frequently asked questions
Common reasons include thermostat settings, a dirty filter, restricted airflow, a defrost issue, refrigerant problems, or an outdoor unit issue. Start with safe checks, then contact a licensed HVAC contractor.
Some frost or light ice in winter is normal because the outdoor coil collects moisture. The defrost cycle should clear it. Heavy, persistent ice usually means the defrost cycle isn't working correctly.
Long runtimes are normal in cold weather, but constant operation without reaching setpoint can indicate undersized equipment, low refrigerant, airflow restrictions, or a defrost issue.
Auxiliary or supplemental heat is a backup heat source — usually electric resistance heat — that the heat pump uses when it can't keep up. Running constantly in mild weather usually indicates a problem to investigate.
Compressor failure, repeated refrigerant leaks, or comfort problems on an older system are common reasons to compare replacement. A written evaluation helps weigh repair vs. replacement.
Yes. HSRC helps homeowners get connected with local licensed HVAC contractors who can evaluate heat pump issues. Availability, pricing, licensing, services, and response times may vary by location and provider.