Freezer shows F6; compressor may not start or may run continuously; temperature unstable.

Safety first: Disconnect power. The compressor circuit carries high voltage and can be hot.

Steps:

• Access compressor compartment: Remove the rear lower cover to expose the compressor and control box.
• Inspect start device: On Liebherr freezers, a PTC or electronic start relay is mounted on the compressor terminals. Check for burn marks, melted plastic, or rattling pieces inside when gently shaken.
• Check connections: Ensure all spade connectors are tight on the compressor and start device.
• Listen for behavior: After reassembling and briefly powering on, listen for a click and short compressor attempt followed by a click-off. Repeated attempts with F6 often indicate a start device issue.

Remedy: Replace the compressor start relay/PTC with the correct Liebherr part. If the new start device does not resolve F6, the main control board or the compressor itself may be faulty and require professional diagnosis.