Direct answer
Auxiliary heat may be normal in cold weather, defrost or large temperature recovery. It is suspicious when it remains active in mild weather after setpoint is reached.
What this covers
- Residential heat pumps with thermostat-displayed AUX or EMERGENCY HEAT
- The exact condition described in the title
- Customer-accessible checks before internal repair or reset
What it does not cover
- ×A different brand, model family or similar-looking code
- ×Internal live-electrical, gas, refrigerant or sealed-system testing
- ×A guarantee that a named component has failed without isolation
Capture the exact state
ReversibleRecord outdoor temperature, thermostat mode, setpoint change and outdoor-unit operation.
Separate the likely fault domains
ReversibleReturn to Heat rather than Emergency Heat, reduce large setpoint jumps and inspect exterior airflow.
Correct only the proven, accessible condition
ReversibleCorrect mode or schedule; arrange service for a non-running outdoor unit or persistent auxiliary heat.
Verify once before going farther
ReversibleHold a steady setpoint and confirm AUX drops out after recovery.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Exact questions
Common follow-ups
What should I record first for “Heat pump auxiliary or emergency heat stays on”?+
Record outdoor temperature, thermostat mode, setpoint change and outdoor-unit operation.
Does the symptom or code prove a part has failed?+
No. Return to Heat rather than Emergency Heat, reduce large setpoint jumps and inspect exterior airflow.
When should I stop troubleshooting?+
Stop for electrical odor, damaged disconnect, heavy ice, refrigerant damage or repeated breaker trips.
Answer for the exact device and software version shown above.