Heat Pump Not Heating

If your heat pump is running but the house is not getting warm, start with thermostat settings, airflow, power, and obvious outdoor-unit conditions.

A heat pump can also produce supply air that feels cooler than furnace air while still heating the house normally.

The key question is whether indoor temperature is maintaining or rising toward the setpoint.

For the broader repair decision, see the heat-pump repair guide.

Safety: Stop troubleshooting for burning smells, damaged wiring, severe mechanical grinding, or repeated breaker trips. If it is safe to use the thermostat, switch the system Off and call a qualified HVAC technician. For smoke or fire, move away from the equipment and contact emergency services.

Sources: Carrier heat pump troubleshooting, Carrier emergency guidance

1. Check the Thermostat

Confirm:

• mode is set to Heat
• setpoint is above room temperature
• schedule has not overridden the setting
• thermostat batteries are good where applicable
• "Emergency Heat" is not accidentally selected unless intentionally needed

Give the system time to respond after changing modes.

2. Check the Air Filter

A heavily clogged filter can reduce airflow.

Inspect the filter and replace it if it is visibly dirty and due for replacement.

Use the correct size/type for the equipment.

Do not remove filtration permanently to increase airflow.

3. Check Supply and Return Airflow

Confirm:

• supply registers are open
• return grilles are not blocked
• furniture/rugs are not obstructing airflow

If airflow is weak throughout the house, the cause can be filter, blower, duct, coil, or control related.

4. Check the Breakers Once

Confirm that relevant breakers have not tripped.

If a breaker is tripped, one reset may be appropriate only if you know which circuit it serves and there is no burning smell, smoke, damaged wiring, or water near electrical equipment. Otherwise, leave it alone and call a professional.

If it trips again:

stop resetting it and call a professional.

Repeated trips indicate an electrical fault or overload that needs diagnosis.

5. Look at the Outdoor Unit

Clear obvious loose debris or heavy snow blocking airflow around the unit without opening the cabinet.

Some frost can be normal in heating mode.

A thick block of persistent ice is not.

Heat pump freezing up

6. Is the Heat Pump in Defrost?

Heat pumps periodically defrost the outdoor coil in cold, damp weather.

During defrost:

• outdoor fan may stop
• steam may appear
• system sound may change
• auxiliary heat may operate

A normal defrost cycle is temporary.

Persistent icing or repeated unsuccessful defrost requires service.

7. Is the Air Warm Enough?

Heat-pump supply air often feels less hot than furnace air.

That can be normal.

Judge performance by:

• room temperature
• thermostat setpoint
• runtime
• ability to maintain comfort

Heat pump blowing cold air

Common Causes of No Heat

Possible causes include:

• thermostat/control fault
• airflow restriction
• blower problem
• outdoor fan problem
• defrost problem
• reversing-valve problem
• refrigerant leak
• compressor problem
• sensor/control-board issue
• backup-heat fault
• duct problem
• electrical problem

Several produce similar symptoms.

Diagnosis matters.

Why Does Auxiliary Heat Run Constantly?

Possible reasons include:

• very cold weather
• thermostat recovery after a large setback
• heat pump unable to meet load
• equipment fault
• bad staging/control settings
• undersized heat pump
• excessive building heat loss

Constant auxiliary heat combined with unusually high bills deserves investigation.

Heat pump electricity usage

Should You Repair or Replace?

A young heat pump with one repair usually belongs in the repair column.

An older system with repeated major failures may deserve a replacement quote.

• Heat pump repair cost
• Heat pump replacement

Find a Heat Pump Repair Technician

If the basic checks do not restore heat, get the system professionally diagnosed rather than replacing random parts.