Freezer shows E4 and may not defrost; ice accumulates on evaporator and rear wall, fan may become noisy or blocked by ice.

Safety first: Unplug the freezer. The defrost heater and wiring are near sharp metal and can be wet; wear insulated gloves and avoid contact with water.

Step-by-step checks:

• 1. Manually defrost: Remove food, unplug the unit, and leave the door open until all ice on the rear wall and evaporator melts. This will temporarily restore airflow and cooling.
• 2. Access evaporator and heater: Remove the interior rear panel to expose the evaporator. The defrost heater is usually a metal or glass-encased element clipped under or around the evaporator.
• 3. Test heater continuity: Disconnect heater leads and measure resistance with a multimeter. A typical heater will show a finite resistance (tens to hundreds of ohms). An open reading indicates a failed heater.
• 4. Check defrost thermostat / thermal fuse: Locate the defrost thermostat or thermal fuse attached to the evaporator tubing. Test for continuity at freezer temperature (it should be closed when cold). Replace if open.
• 5. Inspect wiring: Follow the heater and thermostat wires back to the harness and PCB. Repair any burnt, brittle, or broken wires.
• 6. PCB / relay check: If heater and thermostat test OK, the main control PCB may not be sending power to the heater. This requires live testing and is best done by a professional.

When to call a technician: If you are not experienced with electrical testing or if the PCB or relay is suspected, contact a Gram service technician.