Freezer shows F4 and interior light or fan may not operate correctly

Safety first: Disconnect power before removing trims or switch housings.

Steps:

• 1. Check door behavior: Open and close the door while observing the interior light and fan. If they do not respond, the door switch circuit is suspect.
• 2. Locate door switch: On many Miele freezers, the door contact is a magnetic reed switch embedded in the cabinet frame or a small switch behind a plastic cover near the hinge side.
• 3. Test with a magnet: With the door open and power on, hold a small magnet over the switch location. If the light goes off and the fan starts, the reed switch is working and the door magnet or alignment may be the issue.
• 4. Inspect door magnet: Check the door seal area for the embedded magnet or plastic magnet block. Ensure it is not loose, missing, or damaged.
• 5. Electrical test: With power off, access the switch wiring and test continuity while activating the switch with a magnet or by pressing it (if mechanical). Replace the switch if it does not change state.
• 6. Check harness and PCB: If the switch tests good, inspect wiring to the control board and the board's input connector for damage or corrosion.

Note: A faulty door switch can also prevent the evaporator fan from running, leading to poor cooling and ice buildup.