Most homes built in Loudoun and western Prince William since the early 2000s heat with a heat pump, and searches for heat pump repair in Virginia climb from under 1,000 a month in September to nearly 10,000 in January. The complaint is almost always one of three things: the heat pump is blowing cold air, the outdoor unit is a block of ice, or the thermostat says AUX or EM HEAT and the electric bill has doubled. A heat pump blowing cold air isn’t always broken, but the version that is broken gets expensive fast if you let the backup strips carry the house.
In this article
Heat pump blowing cold air: what each symptom means
| Symptom | Likely cause | DIY-safe? | Needs a tech? |
|---|---|---|---|
| Air is lukewarm, not hot | Normal — heat pumps deliver 85–95°F air, cooler than a furnace | Check with a thermometer | No |
| Cool air for 5–10 minutes, then warm | Defrost cycle; normal in freezing, damp weather | Wait it out | No |
| Cool air constantly in heat mode | Reversing valve stuck, low refrigerant, or outdoor unit not running | Check the outdoor fan | Yes |
| Outdoor unit solid ice, fan stopped | Defrost board or sensor failed, or fan motor dead | Turn it off | Yes — same day |
| AUX / EM HEAT on most of the time | Heat pump can’t keep up: compressor, capacitor, refrigerant, or thermostat setup | Check thermostat settings | Yes |
| Loud hum, outdoor fan not spinning | Failed capacitor or fan motor | No | Yes |
Heat pump blowing cold air? Six safe checks
- Measure, don’t guess. Hold a thermometer at a supply vent. 85–95°F is normal heat-pump output; it feels cool against skin because it’s below body temperature.
- Watch a defrost. On a cold, damp morning the unit will reverse for a few minutes, steam, and blow cool inside. That’s designed behavior, not a fault.
- Look at the outdoor unit. Light frost on the coil is normal. Ice bridging the fins, or a fan sitting still while the unit hums, is not. Turn it off and call.
- Check the thermostat. It should be set to HEAT, not EM HEAT. Emergency heat bypasses the heat pump entirely and runs on strips.
- Clear the coil. Leaves, mulch and snow piled against the outdoor unit block airflow. Keep two feet clear.
- Replace the filter. Restricted indoor airflow makes the system freeze up and trip into auxiliary heat.
Heat pump blowing cold air and AUX heat: the expensive symptom
Electric resistance backup costs roughly three times as much per degree as the heat pump itself. A system that’s quietly running on strips because the compressor is weak or the refrigerant is low won’t leave you cold; it will leave you with a January bill two or three hundred dollars higher than last year. If the thermostat shows AUX for more than a few minutes at a time when it’s above 30°F outside, you have the same fault as a heat pump blowing cold air, and it is worth fixing now.
What a heat pump blowing cold air repair usually involves
Dual-run capacitors, contactors, defrost control boards, defrost sensors, outdoor fan motors and reversing-valve solenoids are all single-visit parts on Carrier, Bryant, Trane, Lennox, Goodman, Rheem, York, Mitsubishi and Fujitsu systems. Refrigerant leaks at flare fittings on mini-splits are repairable. A failed compressor on a system past 12–15 years is the one case where replacement usually wins, and we’ll say so before any work.
Appliances Pro Inc — rated 4.8★ by 513 Google reviewers, serving Northern Virginia since 2008. Open 7 days, 5 AM–10 PM. Free service call with any completed repair, 90-day parts and labor warranty.
Heat pump blowing cold air in the middle of the night
Overnight is when a heat pump blowing cold air is most noticeable, because outdoor temperatures drop, defrost cycles run more often, and the system spends more time near its balance point. A few minutes of cool air on a freezing, damp night is a defrost and nothing more. A heat pump blowing cold air for a full hour with the outdoor fan silent is a failure, and it is worth switching the thermostat to EM HEAT until morning so the house stays warm and the compressor is not run against a stuck reversing valve. Note the time and the outdoor temperature; that detail shortens the diagnosis when you call.
When to call about a heat pump blowing cold air
- A heat pump blowing cold air in heat mode that doesn’t warm up after 15 minutes
- The outdoor unit is iced solid or the fan won’t spin
- AUX or EM HEAT shows most of the time
- The outdoor unit hums but doesn’t start
- Your electric bill jumped with no change in weather
Call (703) 916-1130 or book online. Same-day service is usually available when you call before noon. Every completed repair includes a FREE service call, and all work carries a 90-day parts and labor warranty.
See our heat pump repair page for more detail, and if you’re nearby, our appliance repair in Ashburn VA team can usually work you into the schedule quickly. For manufacturer support resources, see trane.com resources.
Frequently asked questions
Is a heat pump blowing cold air normal?
Somewhat. Heat pump supply air is 85–95°F, which feels cool to the hand but heats the house fine. Brief cool air during a defrost cycle is also normal. Constant cool air, or a house that can’t hold temperature, is not.
Why is my heat pump covered in ice?
The defrost cycle isn’t running: a failed defrost board or sensor, a dead outdoor fan, or restricted airflow. Running it iced over damages the compressor, so switch to emergency heat and call the same day.
Why does my thermostat say AUX heat?
The heat pump couldn’t meet the thermostat’s call, so the electric backup strips turned on. Occasionally on very cold days is normal. Most of the time, it means the heat pump is underperforming and costing you money.
How much does heat pump repair cost?
We charge a service call fee to diagnose, waived if you proceed with the repair, and quote before any work. Capacitors, contactors, defrost boards and sensors are inexpensive; compressors are not, and we’ll walk you through repair-or-replace honestly.