Wine cooler displays E4 and may stop cooling or enter a defrost-like mode; compressor and fan may be off for extended periods.

Safety warning: Disconnect power before accessing the evaporator and electrical components. Avoid contact with sharp fins and live wires.

Inspection and testing:

• Access evaporator compartment: Remove interior shelves and the rear inner panel to expose the evaporator coil and defrost components.
• Locate defrost sensor and heater: The defrost sensor is usually clipped to the evaporator tubing; the heater is a tube or wire element at the base or wrapped around the coil.
• Check for heavy ice buildup: If the evaporator is a solid block of ice, unplug the unit and allow it to fully defrost (this may take several hours). Place towels to catch water.
• Test defrost sensor: Disconnect the sensor and measure resistance at room temperature and again in ice water (~0°C). Resistance should change significantly. If open or shorted, replace the sensor.
• Test defrost heater: With the unit unplugged, measure resistance across the heater terminals. A typical reading is between 50–300 Ω. Infinite resistance indicates an open heater that must be replaced.
• Inspect wiring and connectors: Look for burnt connectors, melted insulation, or loose plugs between heater, sensor, and main PCB.
• Control board check: If both sensor and heater test good, the defrost relay or control logic on the main PCB may be faulty. Replace the main control board.

Note: Do not use sharp tools to remove ice; you can puncture the evaporator and cause a refrigerant leak.