Freezer making loud rattling or clunking noise when compressor starts or stops

Safety first: Unplug the freezer before accessing the rear. Compressor can be hot.

Steps:

• Inspect mounts: Remove the rear panel and check that the compressor is firmly held by its mounting bolts and rubber grommets.
• Tighten hardware: Gently tighten loose mounting bolts, but do not overtighten and crush the rubber mounts.
• Check tubing: Ensure refrigerant lines are not touching each other or the cabinet. Gently bend them away to prevent rattling.
• Evaluate noise: If the compressor itself makes loud internal knocking, it may be failing. Continued operation is possible but may lead to eventual compressor replacement by a professional.