Interior light works but compressor and fans do not run; display may show normal temperatures.

Safety first: Unplug the refrigerator before accessing rear components.

Steps:

• 1. Check for demo mode: Some Siemens models have a showroom/demo mode where cooling is disabled. Refer to the user manual to exit demo mode (often a specific button combination).
• 2. Listen for relay click: When the unit calls for cooling, you should hear a click from the control board area. No click may indicate a failed relay or control logic.
• 3. Inspect compressor start device: Remove the start relay/overload from the compressor and test as described in compressor start fault procedures. Replace if defective.
• 4. Evaluate sensors: A sensor reading incorrectly warm or cold can prevent compressor operation. Test NTC sensors and replace if out of spec.
• 5. Replace main PCB: If start components and sensors are good but the compressor never receives power, the main control board likely needs replacement.

Note: Allow several minutes after power-up for the control to initiate compressor operation; many models have a built-in delay.