Freezer display shows E4; unit may stop defrosting properly or may over-defrost, causing warm temperatures or ice buildup.

Safety: Unplug the freezer and allow sharp metal parts to warm slightly before working near the evaporator.

Steps:

• Access evaporator area: Remove baskets and the rear interior panel to expose the evaporator coil.
• Locate defrost sensor/thermostat: It is usually a small round or bullet-shaped device clipped to the evaporator tubing, or a sensor in a plastic housing attached to the coil.
• Check attachment: Ensure the thermostat/sensor is firmly clipped to the tubing; if it has come loose, reattach it securely.
• Test continuity: For a thermostat-style device, test continuity with a multimeter when the evaporator is cold (below freezing). It should show continuity when cold. If it remains open, replace it.
• Inspect wiring: Look for brittle insulation, burn marks, or broken connectors. Repair or replace damaged wiring.
• Replace component: Install a new defrost thermostat / defrost sensor compatible with your Vissani model if testing indicates failure.
• Control board: If the sensor and wiring are good but E4 persists, the main control board may not be reading the sensor correctly and may need replacement.

Tip: After repair, manually defrost any heavy ice buildup before returning the freezer to service.