Freezer produces a knocking or banging sound when the compressor starts or stops.

Safety first: Unplug the freezer before working near the compressor.

• Inspect compressor mounts: Remove the rear cover and gently check that the compressor mounting bolts or rubber grommets are intact. Tighten slightly if obviously loose, but do not overtighten.
• Check tubing: Look for copper refrigerant lines touching each other or the cabinet. Gently bend them away a few millimeters to prevent contact, taking care not to kink the tubing.
• Reinstall cover: Replace the rear cover securely to reduce noise transmission.

When to call a technician: If knocking is very loud or accompanied by poor cooling, the compressor may be failing and needs professional evaluation.