Indoor unit displays F4, unit may stop during operation

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Extremely dirty indoor filter or coil, Low refrigerant charge, Indoor fan not running or running too slow, Faulty coil thermistor reading

Safety first: Turn off power before cleaning or inspecting internal parts.

Steps:

Clean filters and coil: Wash filters and clean the evaporator coil with a soft brush or coil cleaner.
Check indoor fan: Ensure the fan runs at all speeds and that airflow is strong. Replace the fan motor if it is weak or intermittent.
Inspect coil thermistor: Confirm the thermistor is properly attached to the coil and wiring is intact.
Refrigerant check (technician): If airflow is good and F4 persists, a technician should check refrigerant charge and system operation.

Medium 3/5

Indoor Fan Motor or Coil Thermistor

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