Wine cooler beeps and displays E4; unit may stop cooling or run erratically.

Safety: Unplug the wine cooler. Allow any ice to melt before working near the evaporator and heater.

• Access evaporator and defrost components: Remove interior shelves and the rear inner panel to expose the evaporator coil, defrost heater, and defrost sensor.
• Inspect for heavy frost: Excessive ice buildup indicates a defrost failure. Note the condition before defrosting.
• Test defrost sensor: Disconnect the defrost sensor and measure resistance with a multimeter. Compare to NTC specs. Replace if open, shorted, or out of range.
• 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.
• Check wiring and connectors: Inspect harnesses from the evaporator area to the main PCB for damage or corrosion. Repair or replace as needed.
• Control board: If sensor and heater test good, the defrost relay or control circuit on the main PCB may be faulty. Replacement of the main PCB is recommended and should be done by a qualified technician.