What should you do first?
Confirm the thermostat is in the correct mode, check the filter, and give the system time to respond. Light outdoor frost can be normal, but heavy persistent ice, a unit that never completes defrost, repeated breaker trips, or no temperature change needs diagnosis.
Safe first checks
Before requesting repair
- Confirm Heat, Cool, or Emergency Heat has not been selected accidentally
- Check the filter and open vents
- Observe whether the outdoor fan operates and whether frost is light or heavy
- Note if auxiliary heat stays on continuously or the system cycles rapidly
Stop and call
Warning signs that need more caution
- Heavy ice that does not clear
- Breaker trips, burning odor, or loud electrical buzzing
- Outdoor fan not turning while the compressor appears to run
- No heat during freezing conditions
- Water or ice creating an electrical or slip hazard
Possible causes
What may be behind the symptom
Airflow or indoor-unit issue
A filter, coil, blower, or duct problem can reduce both heating and cooling performance.
Defrost or outdoor control fault
Sensors, boards, valves, motors, and controls manage cold-weather operation and can allow excessive ice when they fail.
Refrigerant or compressor fault
Leaks, reversing-valve problems, metering faults, and compressor issues require professional instruments and training.
Professional diagnosis
What a technician may inspect
- Operating mode and thermostat configuration
- Airflow and temperature change
- Defrost sensors, board, outdoor coil, and fan
- Electrical components and compressor operation
- Refrigerant-side performance and reversing-valve behavior
Cost context
What can affect repair price?
- The system type, capacity, age, and accessibility
- The failed component and whether compatible parts are available
- Diagnostic or service-call fees in the local market
- After-hours timing and current provider availability
- Refrigerant type, electrical work, and any additional testing required
Common questions
Frequently asked questions
Is frost on a heat pump always a problem?
No. Light frost can be normal and should clear during defrost. Thick ice that persists or returns quickly can indicate an airflow, defrost, control, or refrigerant problem.
Why does heat-pump air feel less hot than furnace air?
Heat pumps often deliver a lower supply-air temperature for longer periods. The key question is whether the home reaches and maintains the thermostat setpoint.
Should I switch to emergency heat?
Use it according to the equipment or thermostat instructions, usually when the outdoor unit cannot operate. It may cost more to run and does not replace diagnosis.
Can a heat pump be repaired in winter?
Yes, subject to diagnosis, weather-safe working conditions, parts, and provider availability.