Display shows E4 and compressor or fan may not start or may cycle rapidly.

Safety: Unplug the unit. The defrost heater and wiring can be live and hot during operation.

• Access evaporator compartment: Remove interior rear panel to expose the evaporator coil, defrost heater, and defrost sensor/thermostat.
• Check for heavy ice: If the evaporator is encased in ice, manually defrost with towels and a fan (do not use sharp tools or open flame).
• Inspect defrost sensor/thermostat: Locate the small round thermostat or NTC sensor clipped to the evaporator. Check for cracks, burn marks, or loose mounting.
• Test continuity: With a multimeter, test the defrost thermostat (if present) for continuity when cold. It should be closed (low resistance) below its cut-in temperature. Replace if open when cold.
• Test defrost heater: Disconnect heater leads and measure resistance. A typical heater will show a finite resistance (e.g., 50–300 Ω). If open (OL), replace the defrost heater assembly.
• Inspect wiring and connectors: Look for burnt connectors or melted insulation. Repair or replace damaged wiring.
• Control board: If heater and sensors test good, the main control board defrost relay or circuit may be faulty and require replacement.