Display shows E4 and compressor or fans may not run correctly.

Safety: Unplug the unit. Components around the evaporator can be sharp and may have residual moisture.

Steps:

• 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.
• Locate defrost sensor: The defrost thermistor is usually clipped to the evaporator tubing or mounted near the top of the coil. It may be separate from the evaporator temperature sensor.
• Inspect wiring: Look for broken or brittle wires, especially where they exit the foam insulation. Repair any obvious breaks with proper crimp connectors and heat-shrink tubing.
• Test defrost sensor: With the unit unplugged, disconnect the sensor and measure resistance. At freezing temperatures, NTC sensors will have higher resistance than at room temperature. An open or shorted reading indicates failure.
• Check defrost heater (if present): Some Magic Chef wine coolers use a small heater or warm loop. Measure continuity across the heater terminals. No continuity means the heater is open and must be replaced.
• Control board: If both sensor and heater test good, the defrost relay or control logic on the main board may be faulty. Replace the main control board.
• Manual defrost: As a temporary measure, fully defrost the unit by unplugging and leaving the door open until all ice melts, then restart. This will not fix the underlying issue but may restore cooling for a short time.