My Heat Pump Is Not Heating (Troubleshooting Guide)

On this page

Quick answer
Confirm the symptom
Tools and prep
Step-by-step troubleshooting
Common causes table
Parts matching
When to call a pro
FAQ
Related guides

Quick answer

Check the thermostat settings, ensure the power is on, and verify the emergency heat setting. If the issue persists, inspect the air filter and outdoor unit for obstructions.

Confirm the symptom

Heat pump is not producing warm air
Thermostat shows heating mode but no heat
Outdoor unit is not running during heating mode

Tools and prep

Thermostat
Screwdriver set
Vacuum cleaner
Flashlight
Multimeter (optional)
Safety gloves
Ladder (if needed for outdoor unit)

Step-by-step troubleshooting

Check Thermostat Settings
Do: Verify the thermostat is set to 'Heat' mode and the temperature is set higher than the current room temperature.
Observe: Thermostat displays correct mode and temperature.
Means: Thermostat settings are correct.
Next: If settings are correct, proceed to the next step. If not, adjust settings and wait 15 minutes to see if heat starts.
Verify Power Supply
Do: Check the circuit breaker or fuse box to ensure the heat pump is receiving power.
Observe: Breaker is not tripped or fuse is intact.
Means: Power supply is normal.
Next: If power is normal, proceed to the next step. If not, reset the breaker or replace the fuse and test the heat pump.
Check Emergency Heat Setting
Do: Look for an 'Emergency Heat' or 'Aux Heat' option on the thermostat and ensure it is not activated unnecessarily.
Observe: Emergency heat setting is off or only activated when needed.
Means: Heat pump is using the correct heating source.
Next: If emergency heat is off, proceed to the next step. If it was on, turn it off and wait 15 minutes.
Inspect Air Filter
Do: Locate and remove the air filter from the indoor unit. Check for dirt or blockage.
Observe: Air filter is clean or dirty.
Means: A dirty filter can restrict airflow and reduce heating efficiency.
Next: If the filter is dirty, replace or clean it and wait 15 minutes to see if heat improves. If clean, proceed to the next step.
Check Outdoor Unit
Do: Inspect the outdoor unit for ice buildup, debris, or obstructions.
Observe: Outdoor unit is free of ice and debris.
Means: Outdoor unit is functioning properly.
Next: If the unit is clear, proceed to the next step. If there are obstructions, clear them and wait 15 minutes.
Test Heat Pump Operation
Do: Set the thermostat to a higher temperature and observe the heat pump's operation.
Observe: Heat pump starts and runs normally.
Means: Heat pump is responding to the thermostat signal.
Next: If the heat pump starts, continue monitoring. If it does not, consider professional assistance.
Check for Error Codes
Do: Look for any error codes or indicator lights on the thermostat or indoor unit.
Observe: Error codes or lights are present or not.
Means: Error codes can indicate specific issues with the heat pump.
Next: If error codes are present, refer to the user manual for troubleshooting. If no codes, proceed to the next step.
Inspect Refrigerant Levels
Do: Check for signs of refrigerant leaks, such as hissing sounds or ice on the coils.
Observe: No signs of refrigerant leaks.
Means: Refrigerant levels are adequate.
Next: If no leaks are found, proceed to the next step. If leaks are suspected, contact a professional technician.

Common causes

Cause	Likelihood	Difficulty	Part often needed
Incorrect Thermostat Settings The thermostat may be set to 'Cool' or 'Off' instead of 'Heat'.	Common	Easy	None
Power Supply Issues A tripped circuit breaker or blown fuse can cut power to the heat pump.	Common	Easy	Circuit breaker or fuse
Dirty Air Filter A clogged air filter restricts airflow and reduces heating efficiency.	Common	Easy	Air filter
Outdoor Unit Obstruction Debris or ice buildup on the outdoor unit can prevent proper operation.	Common	Easy–Medium	None
Refrigerant Leak Low refrigerant levels can prevent the heat pump from heating effectively.	Sometimes	Hard	Refrigerant
Faulty Defrost System A malfunctioning defrost system can cause ice buildup on the outdoor unit.	Sometimes	Medium	Defrost system components
Thermostat Malfunction A faulty thermostat may not send the correct signals to the heat pump.	Sometimes	Medium	Thermostat
Compressor Issues A malfunctioning compressor can prevent the heat pump from generating heat.	Rare	Hard	Compressor

Parts matching

If you need to replace parts, match these common issues with the right components:

Dirty air filter → Replace with a new air filter
Tripped circuit breaker → Reset or replace the circuit breaker
Faulty thermostat → Install a new thermostat
Refrigerant leak → Hire a professional to recharge refrigerant
Defrost system issues → Replace defrost system components if damaged

Always refer to your heat pump's user manual for specific part compatibility and installation instructions.

When to call a professional

The heat pump still does not heat after following all troubleshooting steps
You suspect a refrigerant leak or compressor issue
Error codes indicate complex issues beyond basic troubleshooting
You are unsure about electrical components or refrigerant handling
The heat pump is making unusual noises or emitting strange odors

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 less efficient in extreme cold. Consider using a supplemental heating source if temperatures drop significantly.

What is emergency heat, and when should I use it?

Emergency heat is a backup heating source that activates when the heat pump cannot meet heating demands. Use it only when necessary, as it consumes more energy.

Why is my heat pump making a buzzing noise?

A buzzing noise may indicate an electrical issue or a problem with the compressor. Turn off the power and contact a professional technician.