Freezer not cooling at all; interior light works but temperature remains at room temperature.

Safety first: Unplug the freezer before accessing the compressor or control board.

• Check basic operation: Listen for compressor and fan noise when the unit is plugged in and the door is closed. If only the light works, cooling is not starting.
• Verify settings: Ensure the freezer is switched on and not in a demo or standby mode. Set temperature to the coldest setting and wait several minutes.
• Inspect compressor area: Remove the rear lower panel. Check if the compressor is warm or completely cold. A cold compressor that never attempts to start suggests a control or start device issue.
• Check start relay: Remove the compressor start device and inspect for burning or rattling pieces. Replace with an OEM De Dietrich start relay/PTC if suspect.
• Control board output (advanced): A technician can check if the board is sending power to the compressor. If not, the board may need replacement.

If the compressor runs but there is still no cooling and no frost on the evaporator, a sealed-system problem (refrigerant leak or blockage) is likely and requires a refrigeration specialist.