Display shows E4, freezer may not defrost, heavy frost on back wall or evaporator, airflow reduced.

Safety first: Unplug the freezer before accessing the evaporator, heater, or control board. The defrost heater operates at line voltage and can cause shock.

• Step 1 – Manually defrost: Remove food to a cooler. Open the door and allow the unit to defrost naturally with towels to catch water, or use a fan to speed melting. Do not use knives or heat guns.
• Step 2 – Access heater: Remove the rear interior panel to expose the evaporator and defrost heater (usually a metal or glass-encased element at the bottom or woven through the coil).
• Step 3 – Continuity test (advanced): Disconnect heater leads and check continuity with a multimeter. An open circuit indicates a failed heater that must be replaced.
• Step 4 – Check defrost thermostat: The defrost thermostat or thermal fuse is clipped to the evaporator tubing. Test for continuity when the thermostat is cold (below freezing). Replace if open.
• Step 5 – If heater and thermostat are good: The main control board or wiring may be at fault. This typically requires schematic tracing and should be handled by a professional technician.