Display shows E4 and the wine cooler may not defrost properly; heavy ice buildup on the evaporator or frequent temperature swings.

Safety: Unplug the unit before accessing the evaporator or electrical components. Allow any ice to melt to avoid slipping and water near live parts.

• Access evaporator area: Remove shelves and inner rear panel to expose the evaporator and defrost components.
• Locate defrost sensor: The defrost NTC is usually clipped to the evaporator tubing or mounted on a bracket near the heater. Inspect for dislodging or damage.
• Check for heavy ice: If the evaporator is encased in ice, allow it to fully defrost (towels and a tray for water). Do not chip ice with sharp tools.
• Test defrost sensor: Disconnect the sensor and measure resistance at near-freezing temperature (0–5°C). Compare to expected NTC values. Replace if open/shorted.
• Test defrost heater: With the unit unplugged, disconnect heater leads and measure resistance. A typical heater will show a finite resistance (tens to hundreds of ohms). If open, replace the defrost heater.
• Inspect wiring and board: Check connectors and harness from heater and sensor to the main PCB. If both components test good, the defrost relay or control board is likely faulty and should be replaced by a professional.