The short answer
A Trane heat pump that seems not to heat in Northern Virginia is often working normally. Its air comes out around 85 to 93 degrees, cooler than your body, so it feels lukewarm. In cold weather it also stops to defrost for a few minutes at a time, with steam off the outdoor unit and its fan stopped. It’s a real problem when the house can’t hold temperature, ice builds on the outdoor coil and doesn’t clear, AUX HEAT stays on for hours when it’s over 40 degrees out, or it cools fine and won’t heat at all.
What’s normal
From Trane’s own pages on heat pumps not heating, the defrost cycle and auxiliary heat:
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| What you notice | Why | Normal? |
|---|---|---|
| The air feels lukewarm | Heat pump air runs about 85 to 93 degrees, under body temperature of 98.6 | Yes |
| Steam, a whoosh, the outdoor fan stops | Defrost: it melts frost off the coil for about 3 to 5 minutes, and it can start once it’s in the low 40s outside | Yes |
| AUX HEAT shows on the thermostat | Backup heat helps when it’s under 40, during defrost, or after you raise the setpoint 3 or 4 degrees | Yes |
| Cool air from the vents between cycles | The fan is set to On, so it runs when the heat isn’t | Set the fan to Auto |
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
Check these first
- The thermostat is on Heat, set a few degrees warmer than the room, fan on Auto.
- The filter. A clogged one cuts airflow, and the heat pump struggles. Change it every 30 to 90 days (filter guide).
- The outdoor unit. Clear snow, ice and leaves off the sides and top by hand; never chip ice off the coil.
- The breakers for the indoor and outdoor units. If one tripped, don’t flip it back; call.
When it’s a real problem
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| What you notice | What it usually is | Typical repair |
|---|---|---|
| Ice building on the coil that defrost doesn’t clear (heat pump covered in ice) | The defrost board or its sensor | $450 to $1,150 |
| AUX HEAT on for an hour or two when it’s over 40 out (aux vs emergency heat) | The heat pump isn’t keeping up: low refrigerant, a defrost fault or a failing part | $99 diagnostic |
| Cools fine all summer, won’t heat now | The reversing valve or its coil | Priced in writing after testing |
| A hiss, or oily spots on the lines | A refrigerant leak | A top-up runs $190 to $740; the leak itself is found and priced in writing |
| Outdoor unit hums and won’t start | The capacitor | $240 to $370 |
| Err 126 on the thermostat (Err 126 guide) | Lost communication with the outdoor unit | $99 diagnostic |
Odd sounds have their own guide (heat pump making noise), and so does cold air (HVAC blowing cold air in winter). For what heat pump repairs run around here, see heat pump repair cost in Northern Virginia.
Emergency heat is a bridge
If the heat pump quits, switching the thermostat to EM HEAT runs the backup strips alone and keeps the house warm until a tech comes. Use it as a bridge, not a fix: strip heat costs a lot more to run than the heat pump does (Trane emergency heat, explained). More on Trane heat pumps in winter is in heat pumps in a Virginia winter, and our heat pump repair page covers what we fix.
What a visit costs
A diagnostic visit is $99, and you get the problem and the price in writing before any work starts. Our heating check is $67 per system, through December 31: furnace, heat pump or boiler. If you want every brand’s codes and lights in one place, our error codes and warning lights guide has them.
Book it
Book the heating check, call (703) 997-9757, or book online from goswiftpro.com/cookiesoffer and a box of warm cookies comes with the visit. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Why is my Trane heat pump blowing cool air?
Often it’s normal. Heat pump air runs about 85 to 93 degrees, cooler than your body, so it feels lukewarm. It also blows cool air during defrost, or between cycles if the fan is set to On.
Why is my Trane heat pump steaming?
It’s defrosting. It melts frost off the outdoor coil for about 3 to 5 minutes, the fan stops, and steam rises off the unit. That’s normal.
When should AUX HEAT come on?
When it’s under about 40 degrees, during defrost, or after you raise the setpoint 3 or 4 degrees. If it stays on for an hour or two when it’s warmer than 40, have the heat pump checked.
Should I use emergency heat?
Only as a bridge until a tech comes. It runs the backup strips alone, which costs much more than running the heat pump.
What does a Trane heat pump defrost board cost?
A defrost board repair runs $450 to $1,150 in Northern Virginia, with the exact price in writing before any work starts.
The system we put in first
Built to take a beating. Put in by our crew.
Heat lamps, snow and rain on one outdoor unit: that’s Trane’s own film. We’re a Trane Comfort Specialist, on Trane’s own dealer locator, and when you pick a Trane, our crew puts it in.
Films: Trane’s own.
