Freezer displays AL01 and beeps; temperature is rising and food is softening.

Safety first: Unplug the freezer before removing any panels. Avoid using sharp tools on plastic parts or the evaporator.

Step-by-step:

• Check door closure: Make sure the door is fully closed and not obstructed by baskets or food. Inspect the door gasket all around for gaps, tears, or hardened sections. If you see frost around the door area, the seal is likely leaking.
• Reduce warm load: If you recently loaded a large quantity of unfrozen food, allow 12–24 hours for the temperature to stabilize. Avoid frequent door openings during this period.
• Verify internal airflow: Listen for the evaporator fan inside the freezer when the compressor is running. If you don’t hear it, remove the internal rear panel (after unplugging) and check for ice buildup around the fan. Defrost fully for 24 hours with the door open and then test again.
• Clean condenser: Pull the freezer away from the wall. Unplug it. Clean the condenser coils and the condenser fan area (if fitted) with a soft brush and vacuum. Ensure there is at least 5–10 cm clearance around the appliance for ventilation.
• Reset alarm: After correcting the issue, close the door, plug the freezer back in, and press the alarm reset or temperature confirmation key (refer to the De Dietrich user interface) to clear AL01. Monitor temperature with a freezer thermometer for several hours.

If AL01 returns quickly despite good sealing and clean coils, the cooling system or control electronics may require professional diagnosis.