| QUICK ANSWER
Most heat pump repair calls trace to one of six causes: a dirty filter or coil restricting airflow, low refrigerant from a leak, a failed reversing valve stopping the switch between heating and cooling, a faulty defrost control leaving the outdoor unit iced over, a capacitor or contactor failure, or a thermostat configured incorrectly for a heat pump. Some things that look like faults are normal — steam from the outdoor unit during a defrost cycle, and longer run times in cold weather, are both expected behaviour. |
| Last updated: October 2026
Reviewed by the licensed technicians at Dead Rock Services family-owned and serving WV, VA & MD since 2015. Licensed in West Virginia, Virginia & Maryland · Authorized Generac dealer · 5.0 stars from 800+ Google reviews. |
Heat pumps behave differently from furnaces, and a lot of service calls turn out to be normal operation that simply looks alarming. Equally, some genuine faults are easy to miss because the system keeps running — just expensively and badly.
Here’s what actually goes wrong with heat pumps, what’s normal in cold weather, and how to tell which you’re looking at before the temperature really drops.
What’s normal — before you call for heat pump repair
Three behaviours that worry homeowners and shouldn’t:
- Steam rising from the outdoor unit. That’s a defrost cycle melting frost off the coil. It’s supposed to happen.
- Longer run times in cold weather. A heat pump delivers gentler heat over longer cycles than a furnace. Running for an extended period isn’t a fault.
- Cooler air from the vents than a furnace produces. Heat pump supply air is typically cooler than furnace air while still heating the home effectively.
What is not normal: ice encasing the outdoor unit for hours, no warm air at all, the system running constantly without reaching temperature, or a sharp jump in your electric bill — which usually means the backup heat strips are running when they shouldn’t be.
The six most common heat pump repair causes
1. Restricted airflow
A clogged filter or a dirty indoor coil is the most common cause of poor performance, and the cheapest to prevent. Check the filter first, always.
H3 2. Low refrigerant
Refrigerant is a sealed system — if it’s low, there’s a leak. Simply topping it up without finding the leak is a temporary fix you’ll pay for again. A proper repair locates and fixes the leak first.
3. Failed reversing valve
The component that lets a heat pump switch between heating and cooling. When it fails, you may get cooling when you want heat. This is a significant repair.
4. Defrost control problems
If the defrost cycle isn’t working, the outdoor coil ices over and the unit can’t extract heat. Persistent heavy ice is the visible symptom.
5. Capacitor or contactor failure
Common electrical failures — humming without starting, or the unit not engaging at all. Both are relatively inexpensive parts.
6. Thermostat not configured for a heat pump
A thermostat that isn’t heat-pump compatible, or is wired or configured incorrectly, can run the backup heat strips constantly. The system heats, but your bill climbs sharply. We find this more often than you’d expect after a DIY thermostat swap.
The backup heat problem worth knowing about
Heat pumps have supplementary electric heat strips for very cold weather. They work, and they are expensive to run. If a fault, a thermostat misconfiguration, or an incorrect balance point leaves those strips engaged more than necessary, your system still heats the house and nothing looks wrong — until the electric bill arrives.
If your heating costs jumped without a rate change or a weather extreme, this is one of the first things worth checking.
What heat pump repair costs
Filter changes, capacitors, contactors and thermostat corrections sit at the low end — a straightforward service call. Refrigerant leak diagnosis and repair sits in the middle and depends on where the leak is. Reversing valve and compressor work sits at the high end, and on an older system those repairs are the point at which replacement deserves a serious look.
We give you the price before the work, and if replacement is the better value we’ll say so rather than selling you a repair that doesn’t pay back.
Maintenance that prevents most of this
Because a heat pump runs year-round, it accumulates far more operating hours than a furnace and benefits from service twice a year. Between visits: change filters on schedule, keep the outdoor unit clear of leaves and vegetation, maintain clearance around it, and make sure snow and ice can’t drift against it. Clearing debris from the outdoor unit in October is a ten-minute job that prevents a lot of January calls.
Frequently Asked Questions
Why is my heat pump blowing cold air?
Briefly, during a defrost cycle, this is normal. Persistently, it points to low refrigerant, a failed reversing valve, or a thermostat configuration problem. If it continues beyond a few minutes, have it diagnosed.
Is ice on my heat pump normal?
Light frost that clears during defrost cycles is normal. Heavy ice encasing the unit for hours is not and usually indicates a defrost control fault or airflow problem. Never chip ice off — you can puncture the coil.
How often does a heat pump need servicing?
Twice a year is appropriate because it runs in both heating and cooling seasons, roughly double the hours of a furnace. Filters need attention more frequently.
Why did my electric bill jump with a heat pump?
Most often the backup electric heat strips are running more than they should — commonly from a thermostat that isn’t heat-pump compatible or is configured incorrectly, or from a fault reducing the unit’s efficiency. It’s worth having checked.