F4 error; compressor may not start or may shut down quickly; often in heating mode.

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

Defective discharge pipe sensor, Sensor not clamped properly to discharge line, Overheating due to blocked outdoor coil, Outdoor PCB misreading sensor

How to Fix / Troubleshooting

Safety: Turn off power and wait for components to cool before touching any pipes.

Steps:

Clean outdoor coil: Remove debris and wash the condenser coil with low-pressure water, avoiding the control box.
Check sensor clamp: Ensure the discharge sensor is tightly attached to the hot gas line and insulated as originally installed.
Replace sensor: If F4 persists, replace the discharge pipe sensor.
Technician check: If a new sensor does not help, the system may be overcharged or have a PCB fault; call a professional.

Repair Difficulty

Hard 4/5

Required Part

Discharge Pipe Temperature Sensor (NTC)

Check Price on Amazon

We may earn a commission from links on this page.