Error E4 displayed; refrigerator may stop cooling periodically or show heavy ice on evaporator.

Safety warning: Unplug the refrigerator before any disassembly. The defrost heater operates at mains voltage.

Steps to diagnose and fix E4 (defrost heater):

• Access the evaporator: Remove freezer drawers and the rear inner panel. Melt any ice buildup with warm air (hair dryer on low, kept at a safe distance) and towels. Do not chip ice with sharp tools.
• Locate the defrost heater: The heater is usually a metal or glass-encased element mounted at the base or around the evaporator coil.
• Visual inspection: Look for burn marks, broken heater tubes, or melted connectors. Check wiring for signs of overheating.
• Test heater resistance: Disconnect the heater from its wiring. Measure resistance with a multimeter; typical values are between 50–300 Ω depending on model. An open circuit indicates a failed heater.
• Check wiring and connectors: Verify continuity from the heater connectors back to the main PCB. Repair any burnt or loose terminals.
• Replace the defrost heater: If faulty, install a new Vestfrost-compatible defrost heater assembly. Ensure it is properly clipped or screwed into place and not touching plastic parts.
• Control board check: If the heater and wiring are good, the defrost relay or triac on the main PCB may be defective. This requires board-level diagnosis or replacement by a technician.

After repair: Reassemble the evaporator cover, restore power, and allow 24 hours for normal frost pattern and temperatures to stabilize.