Display shows E4 and the unit may run continuously or not at all, with defrost issues.

Safety: Disconnect mains power before accessing internal components. Surfaces around the evaporator can be sharp.

• Access evaporator area: Remove the internal rear panel to expose the evaporator and defrost components.
• Locate defrost sensor: The defrost NTC is usually clipped to the evaporator tubing or attached near the defrost heater.
• Check for ice buildup: Heavy ice accumulation can damage the sensor or wiring. Fully defrost the unit if necessary.
• Test sensor: Measure resistance at a known temperature (e.g., after defrost at room temperature). Compare to the NTC curve. Replace if open/shorted.
• Inspect heater and wiring: Check the defrost heater for continuity and inspect wiring harnesses for burns or breaks.
• Replace faulty parts: Install a new defrost sensor (and heater if needed) using original clips and insulation. Ensure good thermal contact with the evaporator.
• Reassemble and test: Refit panels, restore power, and monitor for correct defrost cycles and absence of the E4 code over 24 hours.