System does not start, display is blank, or heat call never reaches equipment.
Set thermostat to Heat, raise setpoint 3-5 degrees, and replace batteries if needed.
Confirm control signal, recalibrate thermostat, and repair wiring/control faults.
Furnace starts briefly then shuts down, or airflow is weak with poor temperature rise.
Replace dirty filter and ensure major supply/return grilles are open.
Measure airflow/static pressure, reset safety controls, and correct root airflow restrictions.
Furnace attempts to start but shuts down quickly and may retry repeatedly.
Listen for startup attempts. Do not disassemble burner compartment.
Clean/replace flame sensor, test igniter performance, and verify safe combustion sequence.
No response from indoor unit or outdoor heat pump during heat call.
Check dedicated HVAC breakers once and reset only one time if tripped.
Find electrical cause of trip, replace failed components, and verify safe amperage draw.
Heat pump runs but delivers cool air, or outdoor unit ices heavily during heating mode.
Check for heavy ice on outdoor coil and whether AUX/EM heat indicator appears.
Test defrost board/sensors, reversing valve operation, and refrigerant performance.
Heat pump runs continuously with little indoor temperature rise.
Temporarily switch to Emergency Heat if system supports it and monitor response.
Verify strip heat staging, relays, and control logic for proper backup heat operation.
Heating stops unexpectedly and may display fault codes.
Look for visible water at equipment base and confirm return vents are not blocked.
Clear drains/venting issues, reset lockout conditions, and test full heating cycle.
Equipment may heat internally but air is not distributed, or system fails to complete cycle.
Turn system off if you smell burning or hear grinding noises.
Perform electrical diagnostics, replace failed controls or motors, and verify safe operation.