Refrigerator making loud buzzing or humming noise from rear, especially when compressor starts.

Safety First: Unplug the refrigerator before accessing the rear compartment.

Steps:

• Identify source: Remove the rear panel and listen carefully (with power on briefly) to locate the noise source—compressor vs. fan.
• Check fan: With power off, spin the condenser fan blade. Tighten or replace if loose or rubbing on shroud. Remove any debris.
• Inspect start relay: If the noise is a repeated loud buzz followed by a click, replace the compressor start relay and overload.
• Check compressor mounts: Ensure rubber grommets are intact and compressor is not contacting the frame directly.