Unit shows E4 and the freezer is warm with heavy ice buildup on the evaporator; fan may be noisy or stopped.

Safety warning: Unplug the refrigerator before any disassembly. The defrost heater operates at mains voltage and can cause electric shock.

Diagnostic steps:

• Defrost the unit: Remove food from the freezer, unplug the appliance, and allow all ice to melt. This may take several hours.
• Access the evaporator and heater: Remove the inner rear panel of the freezer to expose the evaporator coil. The defrost heater is usually a metal or glass-encased element at the bottom or woven through the coil.
• Check the defrost thermostat/fuse: Locate the small round or rectangular thermostat clipped to the evaporator tubing. With the unit still cold, disconnect and test for continuity. If open at freezing temperatures, replace it.
• Test the heater element: Disconnect the heater leads and measure resistance. A typical heater will show a finite resistance (e.g., 50–300 Ω). If it reads open (∞), the heater is faulty.
• Inspect wiring and connectors: Look for burnt connectors, melted insulation, or loose plugs between the heater, thermostat, and main PCB.
• Replace faulty components: If the heater or thermostat is defective, order Gorenje-specific parts for your model. Install the new heater in the same mounting clips and reconnect all wiring securely.
• Reassemble and test: Refit the rear panel, restore power, and monitor over several days. Frost should no longer build up, and E4 should clear.

Note: If heater and thermostat test good, the main control board’s defrost relay or triac may be defective. This typically requires board replacement by a professional.