Alarm and E13 on display; heavy frost on evaporator; temperature unstable.

Safety first: Unplug the unit and allow ice to melt before working near the evaporator and heater. Water may drip; protect the floor.

Steps to check and fix:

• 1. Defrost manually: Switch off the cooler and leave doors open until all ice on the evaporator has melted. Do not use sharp tools.
• 2. Access evaporator assembly: Remove the internal rear panel to expose the evaporator coil, defrost heater, and defrost thermostat/NTC.
• 3. Locate defrost thermostat/sensor: It is usually clipped to the evaporator tubing near the top or middle. Some models use a small round thermostat; others use an NTC probe.
• 4. Test component: For a thermostat, check continuity at freezing temperatures (place in ice water). It should be closed when cold. For an NTC, measure resistance and compare to spec. Replace if readings are incorrect.
• 5. Inspect wiring: Look for brittle or burnt insulation near the heater and thermostat. Repair or replace damaged wiring with high-temperature-rated wire.
• 6. Replace faulty parts: Install a new Vestfrost-compatible defrost thermostat or NTC sensor, ensuring firm contact with the evaporator tubing.
• 7. Reassemble and test: Refit panels, restore power, and monitor for proper defrost cycles. The E13 code should clear once the control detects normal defrost termination.
• 8. If problem persists: A faulty control board defrost circuit may be at fault and should be evaluated by a technician.