Freezer displays AL12; ice or frost may be excessive and defrost cycles seem absent.

Safety first: Unplug the freezer before working on the defrost system. Components may be live and hot during operation.

• Manual defrost first: Switch off and fully defrost the freezer to restore airflow and prevent further damage. This also allows access to the evaporator and defrost components.
• Inspect defrost thermostat/fuse: Look for a small round or inline device clipped to the evaporator tubing. Check for signs of overheating or cracking. Replace if suspect.
• Check heater continuity (advanced): With the heater disconnected and freezer unplugged, use a multimeter to check for continuity. An open reading indicates a failed heater.
• Examine wiring: Follow the wires from the heater and thermostat back to the control board, looking for breaks or burnt connectors.
• Reassemble and test: After replacing any failed components, reassemble panels, restore power, and monitor frost pattern over several days. AL12 should clear once the control detects normal defrost operation.