System stops; E4 error; may occur during heating mode on heat pump models

Safety Warning

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

Blocked outdoor coil, Low refrigerant charge, Faulty discharge temperature sensor, Restricted refrigerant flow (partially blocked expansion valve or filter drier)

How to Fix / Troubleshooting

Safety: Turn off power before cleaning. Refrigerant-side restrictions require a technician.

Clean outdoor coil: Remove dirt and debris from the coil. Ensure good airflow around the unit.
Check outdoor fan operation: Confirm the fan runs at full speed. Replace the fan motor if it is slow or intermittent.
Inspect discharge sensor: Verify the sensor is properly attached to the discharge line and wiring is intact. Replace if damaged.
Technician evaluation: If E4 persists, a technician should check refrigerant charge and look for restrictions in the circuit.

Repair Difficulty

Professional Required 5/5

Required Part

Discharge Temperature Sensor

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