LG Stuck Cooling Fan Relay or Sensor Logic Fault

Microwave fan runs whenever the unit is plugged in, even when not cooking.

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

Welded fan relay on main PCB, Faulty temperature sensor reading high, Control board firmware glitch

How to Fix / Troubleshooting

Safety: Unplug the microwave before any inspection.

User steps:

Power reset: Unplug for 10–15 minutes, then reconnect and see if the fan behavior changes.
Check for overheating: Ensure vents are clear and the unit is not installed too tightly against cabinets.

If the fan still runs continuously, the control board or sensor logic is likely faulty. A technician will need to test and replace the main PCB or sensor as needed.

Repair Difficulty

Hard 4/5

Required Part

Main PCB (Fan Relay)

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