Wine cooler displays E4 and may shut down cooling or run erratically.

Safety warning: Unplug the unit before accessing the evaporator or control board. Avoid contact with sharp fins on the evaporator.

Steps to address E4:

• Check for heavy frost: Remove interior rear panel and inspect the evaporator. If it is encased in ice, the defrost system is likely not working.
• Inspect defrost sensor: Locate the small sensor clipped to the evaporator tubing (often near the top). Check for broken wires or a loose clip. Reseat the connector at the control board.
• Test the defrost sensor: At room temperature, measure resistance with a multimeter. Compare to the expected NTC value. If open or shorted, replace the sensor.
• Check defrost heater (if accessible): With the unit unplugged, disconnect heater leads and measure continuity. A good heater will show low resistance (typically 20–200 ohms). If open, the heater is bad.
• Manual defrost: If the coil is heavily iced, allow the unit to defrost fully by leaving it unplugged with doors open for 24 hours. Protect the floor from water.
• Replace failed components: Install a new Frigidaire defrost sensor and/or defrost heater as needed. Ensure all wiring is reconnected exactly as original.

Note: If sensor and heater test good, the main control board's defrost circuit may be faulty and should be replaced by a qualified technician.