Furnace cabinet vibrates excessively and rattles during blower operation.

Safety first: Turn off power before tightening or adjusting components.

• Tighten screws: Check all access panels and internal mounting brackets for loose screws and tighten them.
• Inspect blower wheel: Look for debris stuck in the wheel or bent blades. Clean and straighten minor bends carefully.
• Level the furnace: Use shims under the furnace base to level it and reduce vibration transfer.
• Secure duct connections: Ensure supply and return ducts are properly supported and not pulling on the furnace cabinet.