Display shows E4 and the unit may not defrost properly, leading to ice buildup on the evaporator.

Unplug the appliance before any disassembly. E4 typically indicates a defrost system problem in Hisense compressor-based wine coolers.

• Inspect for heavy frost: Remove interior shelves and the rear inner panel. If the evaporator is encased in solid ice, the defrost system is likely not working.
• Check the defrost heater: Locate the heater element at the base or around the evaporator coil. Disconnect its wires and measure resistance with a multimeter. A typical heater will show a finite resistance (e.g., 50–300 Ω). An open reading means the heater is bad.
• Check defrost thermostat/thermal fuse: If present, it will be clipped to the evaporator tubing. With the unit at freezing temperature, it should read closed (near 0 Ω). An open reading indicates it has tripped or failed.
• Inspect wiring: Look for burnt connectors or melted insulation around the heater and thermostat wiring.
• Manual defrost: To temporarily restore cooling, allow the unit to defrost fully by unplugging it and leaving the door open for 12–24 hours. Protect the floor from water.
• Replace failed components: Install a new defrost heater or thermostat/thermal fuse as needed, using Hisense-compatible parts. Ensure all connections are tight and insulated.

If the heater and thermostat test good, the main control PCB may not be sending power to the defrost circuit and should be diagnosed or replaced by a professional.