Freezer over-freezing; temperature much lower than set; items near back wall covered in ice.

Safety first: Unplug the freezer before accessing the thermostat or sensors.

• Check settings: Verify the temperature is not set to maximum cold or super-freeze mode on your Fagor freezer.
• Inspect sensor placement: Ensure the cabinet sensor is not touching the evaporator directly unless designed to. Reposition if necessary.
• Test sensor: Measure resistance of the NTC sensor; a shorted sensor will read very low resistance. Replace with an OEM Fagor sensor.
• Mechanical thermostat: On models with a dial thermostat, replace the thermostat if it does not cycle the compressor off when the cabinet is very cold.
• Control board: If the compressor never stops despite correct sensor readings, the control relay may be stuck and the board should be replaced.