Wine cooler shows E4 and may shut down cooling or run continuously; defrost may not function correctly.

Safety first: Disconnect power before accessing the evaporator or control board. Beware of sharp fins and edges.

Steps to troubleshoot E4:

• 1. Inspect for heavy frost: Remove interior rear panel and check the evaporator coil. If it is completely iced over, the defrost system is likely not working.
• 2. Check defrost sensor: Locate the defrost thermistor (often clipped to the evaporator tubing). Inspect for physical damage. Disconnect and test resistance with a multimeter; compare to Vinotemp specs at the measured temperature. Replace if open/shorted.
• 3. Test defrost heater (if equipped): With the unit unplugged, disconnect the heater leads and measure resistance. A reading of infinite resistance indicates a failed heater. Replace with a Vinotemp-compatible defrost heater.
• 4. Inspect wiring and connectors: Look for burnt connectors, melted insulation, or loose plugs between the heater, sensor, and control board.
• 5. Reassemble and reset: After replacing any failed components, reassemble panels, plug in the unit, and allow it to run through a cycle. The E4 code should clear if the defrost circuit is restored.

Note: If the heater and sensor test good, the control board defrost relay or logic may be defective and should be evaluated by a technician.