Heat Pump Runs but House Never Warms Up (Trane & American Standard)
If your heat pump is running constantly but the house never seems to warm up, the system is usually operating but not producing enough heat to overcome heat loss.
What should normally happen
A properly sized heat pump should run steadily in cold weather and slowly raise or maintain indoor temperature, even if the air feels lukewarm. Make sure your outdoor unit is actually running. If not, you have a different issue.
Common causes (most likely first)
- Auxiliary heat not coming on when required
- Thermostat set up incorrectly
- Outdoor temperature below efficient heat pump range (rare, modern heat pumps work below 0 in most conditions)
- Dirty filter or airflow restriction
- System undersized for the home
- A defrost issue (check for ice on outdoor unit. Frost is fine, large amounts of ice are an issue)
Safe homeowner checks
- Check thermostat to see if AUX or EM heat ever appears (it is okay if it does)
- Replace the air filter if dirty or clogged
- Make sure all supply vents are open, as well as interior doors of the home.
- Verify thermostat is set to HEAT, not ECO or AUTO modes that limit aux heat
When this becomes a technician issue
- If auxiliary heat never engages or the system cannot maintain temperature, electrical testing of heat strips, sequencers, or control wiring is required.
- If outdoor unit is frozen (large amount of ice), electrical testing of the defrost board is required.
Parts commonly involved
- Heat strips
- Sequencers or relays
- Thermostat
- Air handler control board
- Air Filters
- Defrost Board or Sensors