Freezer shows AL05; defrost cycles may not occur or may be excessive; frost buildup or temperature swings observed.

Safety first: Unplug the freezer and allow any ice to melt before working near the evaporator or heater. Use towels to collect water.

• Access evaporator area: Remove drawers and the inner rear panel to expose the evaporator, defrost heater, and defrost thermostat/sensor.
• Check for heavy frost: If the evaporator is encased in ice, the defrost system is likely not working. Manually defrost with a hair dryer on low, keeping it moving and away from plastic.
• Inspect defrost thermostat: The Fagor defrost thermostat (or sensor) is usually clipped to the evaporator tubing. Check for cracks or deformation. With the thermostat cold, test continuity with a multimeter; it should be closed when below its cut-in temperature.
• Test defrost heater: Disconnect heater leads and measure resistance. An open circuit indicates a failed heater that must be replaced with the correct Fagor defrost heater element.
• Wiring and relay: Inspect wiring for burns or loose connectors. If heater and thermostat test good, the defrost relay or control board may be faulty and should be replaced by a technician.
• Reassemble and monitor: After replacing faulty parts, reassemble panels, restore power, and monitor for normal frost pattern and absence of AL05.