Freezer makes loud knocking, banging, or rattling noises during operation, especially when the compressor starts or stops.

Safety first: Unplug the freezer before reaching behind or underneath it.

Step-by-step checks:

• 1. Level the unit: Use a spirit level to ensure the freezer is level front-to-back and side-to-side. Adjust the front feet until stable.
• 2. Check external vibrations: Ensure the freezer is not touching walls, cabinets, or other appliances that can amplify noise.
• 3. Inspect compressor mounts: Remove the rear lower panel and check that the compressor mounting bolts and rubber grommets are intact and tight.
• 4. Check refrigerant lines: Gently move copper tubes away from cabinet surfaces if they are touching and rattling. Do not kink or sharply bend the lines.
• 5. Internal fan noise: If noise comes from inside, remove the interior rear panel and check that the evaporator fan is secure and blades are not hitting ice or plastic.

When to call a technician: If knocking persists and seems to come from inside the compressor, the compressor may be failing and should be evaluated by a professional.