Furnace vibrates excessively and causes rattling noises in ducts and casing.

Safety: Turn off power before inspection.

• Tighten fasteners: Check all accessible screws and bolts on the blower housing, flue fan, and casing. Tighten as needed.
• Inspect blower wheel: Look for missing fins or heavy dust buildup on one side. Clean evenly.
• Check duct connections: Ensure supply and return ducts are securely fastened and supported.

If vibration continues, the blower wheel or motor shaft may be bent and should be replaced by a professional.