Heat Pump Not Heating

If a heat pump is not heating, begin with simple observations that do not require opening equipment or touching electrical components. A no-heat complaint can come from settings, blocked airflow, snow and ice, backup-heat controls or an equipment fault.

Check the thermostat or controller

Confirm that the system is in heat mode, not cool, fan-only or off. Raise the setpoint above room temperature and allow the system time to respond. On multi-zone systems, confirm that the affected indoor unit is actually calling for heat.

Check the filters and indoor airflow

Dirty filters can reduce airflow enough to affect comfort. Clean or replace only the filters intended for normal homeowner service. Make sure furniture, curtains or storage are not blocking indoor heads, supply registers or return grilles.

Look at the outdoor unit from a safe distance

Make sure the coil is not buried behind a snowbank and the fan area is clear. Light frost is normal during heating. Steam and water can appear during a normal defrost cycle. Do not remove panels or chip ice from the coil.

Allow for defrost

During defrost, the system temporarily uses heat to clear the outdoor coil. Indoor heating may pause or feel cooler for a short period. The unit should return to normal heating after defrost. Ice that remains, surrounds the fan or quickly returns is a reason to request service.

Check whether backup heat is working

Some systems use electric baseboards, auxiliary heat in an air handler, or a furnace as backup. If the heat pump is operating but the home falls behind only in very cold weather, the issue may involve backup-heat controls, system capacity or both.

When to request repair

• The system previously heated normally but no longer maintains temperature.
• Persistent ice remains after defrost.
• The outdoor unit runs but indoor air remains close to room temperature.
• A new grinding, shrieking or hard mechanical noise appears.
• Water leaks from an indoor unit.
• Fault lights or error codes keep returning.
• A breaker repeatedly trips or there is a burning smell.

If a breaker will not stay on, or there is a burning smell or visible electrical damage, stop trying to restart the system and request professional service.

Do not attempt refrigerant or electrical repairs

Do not open electrical cabinets, bypass safety controls, handle refrigerant or attempt compressor repairs. Those tasks require training, tools and appropriate licensing.

Was the system ever able to heat the space?

A system that used to keep the home comfortable and now cannot is more likely to have a fault. A system that has never heated certain rooms properly may have a sizing, distribution or installation problem rather than a new failure.

Information that helps a technician

Note when the problem started, thermostat mode, any error code, whether the outdoor unit is iced, whether the fans are running, whether backup heat works, and which rooms are affected. That information makes a repair request more useful.