Heat Pump Not Working: Troubleshooting Guide (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

If your heat pump isn't working, first check the thermostat settings and power supply. Ensure the unit is in heating mode and the circuit breaker hasn't tripped. If the issue persists, inspect the air filter and outdoor unit for obstructions.

Confirm the symptom

No heat output from the system
Heat pump won't turn on at all
Thermostat shows no response
Unit runs but doesn't warm the home

Tools and prep

Thermostat
Screwdriver set
Flashlight
Vacuum with brush attachment
Ladder (for outdoor unit access)
Multimeter (optional for advanced checks)
Owner's manual for the heat pump

Step-by-step troubleshooting

Check Thermostat Settings
Do: Verify the thermostat is set to 'Heat' and the desired temperature is higher than the current room temperature.
Observe: Thermostat displays correct settings and responds to changes.
Means: Thermostat settings are correct or need adjustment.
Next: If settings are correct, proceed to step 2. If not, adjust and monitor for heat output.
Inspect Power Supply
Do: Check the circuit breaker or fuse box for tripped switches or blown fuses related to the heat pump.
Observe: Breaker is in the 'On' position and shows no signs of tripping.
Means: Power supply is intact or needs restoration.
Next: If power is off, reset the breaker and test the system. If still no power, proceed to step 3.
Check Air Filter
Do: Locate and inspect the air filter in the indoor unit or air handler. Replace or clean if dirty.
Observe: Air filter is clean and allows unrestricted airflow.
Means: Restricted airflow due to a dirty filter is resolved.
Next: If the filter was dirty, allow the system to run for 10 minutes and check for heat. If no improvement, continue to step 4.
Inspect Outdoor Unit
Do: Use a ladder to access the outdoor unit and clear any debris, ice, or snow from the coils and fan.
Observe: Outdoor unit is free of obstructions and blades spin freely.
Means: Physical blockage is removed, allowing proper operation.
Next: Turn the system back on and check for heat output. If still not working, proceed to step 5.
Verify Emergency Heat
Do: If using a thermostat with emergency heat settings, ensure it's not engaged unless necessary.
Observe: Emergency heat indicator is off or set appropriately.
Means: System is using the correct heating mode.
Next: If emergency heat was on, switch it off and monitor. If no change, move to step 6.
Check for Error Codes
Do: Look at the thermostat or heat pump display for any error codes or blinking lights.
Observe: Error code or indicator is visible and documented.
Means: Specific issue can be identified for further action.
Next: Refer to the owner's manual for code meanings. If unresolved, consider professional help.
Test with Multimeter
Do: Use a multimeter to check for voltage at the indoor and outdoor units to ensure power is reaching the components.
Observe: Voltage readings match expected values from the manual.
Means: Electrical issue is confirmed or ruled out.
Next: If voltage is absent, check wiring. If present but unit still fails, contact a professional.

Common causes

Cause	Likelihood	Difficulty	Part often needed
Thermostat Misconfiguration Incorrect settings can prevent the heat pump from activating the heating cycle.	Common	Easy	None
Tripped Circuit Breaker A tripped breaker cuts power to the heat pump, stopping all operations.	Common	Easy	None
Dirty Air Filter A clogged filter restricts airflow, reducing heating efficiency or causing system shutdown.	Common	Easy	Air Filter
Blocked Outdoor Unit Debris or ice on the outdoor unit obstructs airflow and impairs heat exchange.	Common	Easy–Medium	None
Low Refrigerant Levels Insufficient refrigerant prevents proper heat transfer, reducing or stopping heating output.	Sometimes	Hard	Refrigerant (Professional Handling)
Faulty Defrost Control Board A malfunctioning board fails to initiate the defrost cycle, causing ice buildup and reduced performance.	Sometimes	Medium	Defrost Control Board
Failed Compressor A non-functional compressor cannot circulate refrigerant, preventing heat generation.	Rare	Hard	Compressor
Thermostat Malfunction A faulty thermostat may not send signals to the heat pump, preventing it from turning on.	Sometimes	Medium	Thermostat
Wiring or Electrical Issues Loose or damaged wiring interrupts power to the heat pump components.	Sometimes	Medium	Wiring Kit or Electrical Components
Refrigerant Leak A leak in the refrigerant lines leads to low refrigerant levels and system failure.	Rare	Hard	Refrigerant and Leak Repair Kit

Parts matching

If your troubleshooting identifies a specific part failure, match your symptoms to the right part:

Thermostat issues → Replace thermostat
Dirty air filter → Replace or clean filter
Blocked outdoor unit → Clear debris manually
Low refrigerant → Call a professional for recharge
Failed compressor → Professional repair or replacement
Defrost control board failure → Replace board
Wiring faults → Repair or replace wiring

Always refer to the owner's manual for part specifications and installation instructions.

When to call a professional

The heat pump still doesn't work after following all troubleshooting steps
You detect a refrigerant smell or notice a refrigerant leak
Error codes persist or indicate a serious fault
You hear unusual noises like grinding or loud buzzing
The system is over 10 years old and frequent repairs are needed
You're uncomfortable working with electrical components or refrigerants

FAQ

How long should a heat pump last?

A well-maintained heat pump typically lasts 10–15 years. Regular maintenance can extend its lifespan.

Can I use my heat pump in very cold weather?

Most modern heat pumps operate efficiently down to 20–30°F, but may need supplemental heating in extreme cold.

Why is my heat pump making noise but not heating?

Unusual noises may indicate a failing motor, fan blade issues, or loose components. Turn off the unit and inspect for visible problems.

Is it normal for the outdoor unit to freeze?

Yes, during cold weather the outdoor unit may ice over. The defrost cycle should automatically melt the ice. If ice persists, there may be a defrost system issue.

Can I run my heat pump without a filter?

Running without a filter is not recommended, as it can damage internal components and reduce efficiency. Replace or clean the filter immediately.

What's the difference between emergency heat and regular heat?

Emergency heat uses electric resistance heating as a backup when the heat pump fails. It's less efficient and should only be used temporarily.