Quick answer
If your heat pump isn't heating, first check the thermostat settings and ensure the unit is in heating mode. Then inspect the air filter and outdoor unit for obstructions. If these don't resolve the issue, test the emergency heat setting and consider professional service if needed.
Confirm the symptom
- No warm air from vents
- Heat pump runs but doesn't heat the home
- Thermostat shows heating but no heat output
- Outdoor unit is not operating during heating mode
- Error codes on the thermostat related to heating
Tools and prep
- Thermostat manual
- Screwdriver set
- Flashlight
- Vacuum cleaner with brush attachment
- Safety gloves and goggles
- Multimeter (optional for advanced testing)
Step-by-step troubleshooting
- Check Thermostat SettingsDo: Verify the thermostat is set to 'Heat' mode and the desired temperature is higher than the current room temperature.Observe: Thermostat is in correct mode and temperature setting.Means: Thermostat is functioning as intended.Next: Check air filter condition
- Inspect Air FilterDo: Remove and examine the air filter for dirt or blockage.Observe: Air filter is clean or dirty.Means: A dirty filter can restrict airflow and reduce heating efficiency.Next: Clean or replace the filter if necessary
- Clear Outdoor UnitDo: Inspect the outdoor unit for snow, ice, or debris buildup.Observe: Outdoor unit is clear or obstructed.Means: Obstructions can prevent proper heat exchange.Next: Remove any debris or snow
- Test Emergency HeatDo: Switch the thermostat to 'Emergency Heat' mode and observe if the system heats.Observe: System heats in emergency mode or not.Means: If it heats in emergency mode, the issue may be with the heat pump's outdoor unit.Next: Check for error codes on the thermostat
- Check for Error CodesDo: Look at the thermostat for any displayed error codes related to heating.Observe: Error codes are present or not.Means: Error codes can indicate specific issues like refrigerant leaks or electrical problems.Next: Consult the thermostat manual for code meanings
- Verify Power SupplyDo: Ensure the heat pump's circuit breaker is on and the outdoor unit's power supply is connected.Observe: Power supply is intact or interrupted.Means: A tripped breaker or disconnected power can prevent the unit from operating.Next: Reset the breaker if tripped or reconnect the power
Common causes
| Cause | Likelihood | Difficulty | Part often needed |
|---|---|---|---|
| Dirty air filter Restricts airflow, reducing heating efficiency. | Common | Easy | Air filter |
| Thermostat malfunction Incorrect settings or faulty sensors can prevent proper heating. | Common | Easy–Medium | Thermostat |
| Outdoor unit obstruction Snow, ice, or debris can block airflow and heat exchange. | Common | Easy | None |
| Low refrigerant level Inadequate refrigerant reduces heat transfer efficiency. | Sometimes | Hard | Refrigerant (requires professional refill) |
| Defective auxiliary heat strips Malfunctioning heat strips can prevent supplemental heating. | Sometimes | Medium | Heat strips |
| Electrical issues Tripped breakers or wiring problems can stop the unit from operating. | Sometimes | Medium | Electrical components |
| Refrigerant leak Leaks reduce refrigerant levels, impairing heat pump performance. | Rare | Hard | Refrigerant and repair kit |
Parts matching
Common parts needed for heat pump heating issues include:
- Air filter (replace every 1–3 months)
- Thermostat (ensure it's compatible with your system)
- Heat strips (for auxiliary heating)
- Refrigerant (requires professional handling)
Always match parts to your heat pump model and consult the manufacturer's guidelines for replacements.
When to call a professional
- The heat pump doesn't produce heat even in emergency mode
- Error codes indicate refrigerant leaks or electrical faults
- You suspect a refrigerant leak (dangerous to handle yourself)
- The outdoor unit is frozen and defrost cycle isn't working
- The system makes unusual noises like grinding or squealing
- You're unsure about electrical issues or complex repairs
FAQ
How often should I replace my heat pump's air filter?
Replace the air filter every 1–3 months, depending on usage and indoor air quality.
Can I use my heat pump in very cold weather?
Heat pumps are effective down to about 30–40°F. Below that, they may rely on auxiliary heat, which is less efficient.
What is emergency heat on a heat pump thermostat?
Emergency heat activates auxiliary electric heating strips, bypassing the heat pump. It's more expensive but provides heat when the heat pump fails.
Why is my heat pump making a clicking noise?
A clicking noise may indicate a faulty relay or electrical component. Check the thermostat and outdoor unit for issues.
How can I improve my heat pump's heating efficiency?
Ensure the outdoor unit is clear of obstructions, maintain a clean air filter, and have the system serviced annually.