Display shows E4 and the unit may stop cooling or run erratically, often associated with defrost issues or heavy ice on the evaporator.

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

• Inspect for ice buildup: Remove interior rear panel to view the evaporator. If it is completely iced over, the defrost system is likely not working.
• Check defrost sensor: Locate the defrost NTC (often combined with the evaporator sensor). Test its resistance at room temperature and again in ice water. Replace if readings are inconsistent or out of spec.
• Test defrost heater: With the unit unplugged, disconnect heater leads and measure resistance. A typical heater will show finite resistance (tens to hundreds of ohms). An open circuit indicates a failed heater.
• Inspect thermal fuse/thermostat: Some Artevino models include a thermal fuse or bimetal thermostat clipped to the evaporator. Test for continuity; replace if open.
• Check control board output: If sensors and heater test good, the defrost relay or triac on the main PCB may be faulty. Visual signs include burn marks or swollen components. Board-level repair is advanced; replacement of the main control board is usually recommended.
• Reassemble and test: After replacing any faulty parts, reassemble panels, restore power, and monitor for proper defrost cycles and absence of E4.