Freezer displays F4 and may not defrost, leading to thick ice on the evaporator and poor cooling.

Safety warning: Unplug the freezer before accessing the evaporator or heater. The heater operates at mains voltage.

Troubleshooting steps:

• 1. Access the evaporator: Remove drawers and the inner rear panel to expose the evaporator and defrost heater assembly.
• 2. Locate heater and safety devices: The defrost heater is usually a metal or glass-encased element at the bottom or woven through the evaporator. A thermal fuse or defrost thermostat may be clipped to the evaporator tubing.
• 3. Test the heater: Disconnect heater leads and measure resistance. Typical values are 50–300 Ω. If the heater is open (OL), it must be replaced.
• 4. Check thermal fuse/thermostat: Test for continuity at room temperature. A blown fuse or open thermostat will interrupt the circuit and trigger F4.
• 5. Inspect wiring: Look for burnt connectors, melted insulation, or broken wires around the heater and up to the control board.
• 6. Replace faulty components: Install a new defrost heater and/or thermal fuse/thermostat as needed, matching the original mounting positions and routing.
• 7. Control board check: If heater and safety devices test good, the defrost relay on the control board may be defective. Replace the board if there is no power output to the heater during a forced defrost (this test is best done by a technician).

Professional service: Recommended if you are not comfortable testing live circuits or replacing high‑voltage components.