Display shows E4 and the compressor does not start or stops shortly after starting.

Safety: Disconnect mains power. Work only on the electrical components; sealed system work (refrigerant) must be done by a licensed technician.

• Access compressor compartment: Remove the rear lower service panel to expose the compressor and electrical box.
• Check for overheating: Carefully touch the compressor shell (it may be hot). If extremely hot, allow it to cool before further testing.
• Inspect start device: Remove the plastic cover on the compressor terminals. Check the PTC start relay and overload protector for burn marks, cracks, or loose connections.
• Test start relay and overload: Use a multimeter to check continuity according to Grundig specifications. Replace if open or visibly damaged.
• Replace start device: Install a new Grundig compressor start relay and overload protector, ensuring firm contact on the compressor pins.
• Listen for compressor operation: After reassembly and restoring power, listen for smooth compressor start. If it hums briefly then clicks off, the compressor itself may be locked.
• Call a technician for sealed system issues: If the compressor is seized or drawing excessive current, a professional sealed system repair or compressor replacement is required.