Heat Not Working on Heat Pump (Troubleshooting Guide)

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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 switch. If the issue persists, inspect the air filter and circuit breaker.

Confirm the symptom

Heat pump is not producing warm air
Thermostat shows heat call but no response
System works in cooling mode but not heating

Tools and prep

Thermostat manual
Screwdriver set
Flashlight
Circuit breaker panel access
Safety gloves
New air filter (if needed)

Step-by-step troubleshooting

Check Thermostat Settings
Do: Verify the thermostat is set to 'Heat' mode and the temperature is set higher than room temperature.
Observe: Thermostat displays correct mode and temperature.
Means: Thermostat is functioning correctly.
Next: If settings are correct, proceed to the next step.
Verify Power Supply
Do: Check if the heat pump's power switch is on and the circuit breaker hasn't tripped.
Observe: Power switch is on and breaker is in the 'On' position.
Means: Power supply is intact.
Next: If power is on, move to the next step.
Check Emergency Heat Switch
Do: Locate the emergency heat switch (often on the thermostat or near the air handler) and ensure it is engaged.
Observe: Emergency heat switch is in the 'On' position.
Means: Emergency heat is enabled.
Next: If the switch is on, continue to the next step.
Inspect Air Filter
Do: 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 affect heating performance.
Next: Replace the filter if it's dirty and test the system again.
Test Thermostat Wiring
Do: Turn off power at the circuit breaker. Remove the thermostat cover and check for loose or disconnected wires.
Observe: Wires are securely connected.
Means: Thermostat wiring is intact.
Next: If wiring is secure, proceed to the next step.
Check for Error Codes
Do: Look at the thermostat or heat pump control panel for any error codes or blinking lights.
Observe: Error codes or indicator lights are present or absent.
Means: Error codes can indicate specific issues.
Next: Consult the owner's manual to interpret the codes.

Common causes

Cause	Likelihood	Difficulty	Part often needed
Thermostat Misconfiguration Incorrect settings can prevent the heat pump from activating the heating mode.	Common	Easy	None
Tripped Circuit Breaker A tripped breaker cuts power to the heat pump.	Common	Easy	None
Dirty Air Filter A clogged filter restricts airflow, reducing heating efficiency.	Common	Easy	Air filter
Emergency Heat Switch Off The emergency heat function may be disabled, preventing auxiliary heat from activating.	Common	Easy	None
Thermostat Wiring Issues Loose or disconnected wires can disrupt communication between the thermostat and the heat pump.	Sometimes	Easy–Medium	Wire connectors
Refrigerant Leak Low refrigerant levels can impair the heat pump's ability to transfer heat.	Sometimes	Hard	Refrigerant (requires professional handling)
Failed Auxiliary Heat Strip The electric resistance heating element may be malfunctioning.	Sometimes	Medium	Heating element
Outdoor Unit Malfunction A faulty outdoor unit can prevent the heat pump from operating in heating mode.	Rare	Hard	Outdoor unit repair or replacement
Control Board Failure A failed control board can prevent the system from initiating heating cycles.	Rare	Hard	Control board

Parts matching

If you need to replace parts, match these common components:

Air filter – Replace every 1–3 months depending on usage
Wire connectors – For securing loose thermostat wires
Thermostat battery – If low battery is causing intermittent issues
Emergency heat switch – If the switch is damaged or non-functional
Auxiliary heat strip – If the heating element is faulty

Always refer to your heat pump's model-specific manual for part compatibility.

When to call a professional

The heat pump still doesn't produce heat after checking all basic troubleshooting steps
You detect a refrigerant leak or smell burning/bad odors
Error codes persist or indicate complex issues
You're unsure about handling electrical components or refrigerant
The system makes unusual noises or fails to start

FAQ

Why is my heat pump not switching to emergency heat?

The emergency heat switch might be turned off, or there could be an issue with the thermostat or auxiliary heating element.

How often should I replace my air filter?

Replace the air filter every 1–3 months, depending on usage and filter type.

Can a low thermostat battery cause heating issues?

Yes, a low battery can lead to incorrect settings or communication problems. Replace the battery if needed.

What should I do if I smell gas or burning?

Turn off the system immediately and call a professional technician to inspect for electrical or gas-related issues.