Wine cooler shows E4 and may not defrost properly; ice buildup on rear wall or evaporator.

Safety: Unplug the wine cooler before accessing the evaporator or electrical components. Melt ice with warm air only; never use sharp tools.

Steps:

• Inspect for ice buildup: Remove shelves and the internal rear panel. Check the evaporator for heavy ice accumulation, which indicates a defrost problem.
• Locate defrost sensor: The defrost NTC is usually clipped to the evaporator tubing or mounted in a small plastic housing on the coil.
• Test defrost sensor: Disconnect the sensor and measure resistance. Compare to expected NTC values at the measured temperature (colder coils will show higher resistance). Replace if open or shorted.
• Check defrost heater: Locate the heater element (often a metal or glass tube at the base or woven through the evaporator). Measure its resistance; a typical value is between 50–300 Ω. An open circuit indicates a failed heater.
• Inspect wiring and connectors: Follow the heater and sensor wires back to the main PCB. Look for burnt connectors, broken insulation, or loose plugs. Repair or replace as needed.
• Manual defrost: If the evaporator is heavily iced, allow the unit to defrost fully by leaving it unplugged with the door open for several hours. Protect the floor from water.
• Reassemble and test: After replacing any faulty components, reassemble panels, restore power, and monitor for normal frost pattern and absence of E4.

Note: If heater and sensor are good, the main control board may not be energizing the defrost circuit and may require replacement.