Rattling or vibrating noise from the cabinet during operation.

Safety first: Turn off power before tightening any components.

• Check panels: Press on each side panel and the top grille while the unit is running (briefly, with caution) to identify which area changes the noise.
• Tighten screws: With power off, tighten all accessible panel screws and fan grille fasteners.
• Inspect compressor mounts: Look at the rubber isolation mounts under the compressor. Replace any cracked or missing mounts.
• Add isolation: If the pad is uneven, consider shimming or adding vibration pads under the unit to reduce transmitted noise.