Unpleasant rattling, squealing and squeaking noises coming from your furnace can be a nuisance during cold months. Not only do they diminish your unit's performance, they can be quite annoying. Common causes of furnace noises include a damaged belt and loose cover panels. Troubleshooting these problems improves your unit's performance and maximizes energy output.
Check the cover panels on your furnace if you hear consistent rattling noises when your unit runs. Tighten the screws on cover panels.
Shut off your unit if you hear squealing or squeaking noises. Remove the screws on the cover panels and then push the panels aside. Remove the bolts that hold the blower motor. Inspect the blower pulley. If the belt is off the pulley, realign it. Refer to your manual if you are unsure how to access the blower pulley on your particular unit.
Purchase a replacement belt from hardware or appliance stores and replace a worn-out belt. Do not over-tighten the belt as this can wear out the motor bearings.
Inspect the duct runs and listen for pinging or popping sounds from the ductwork. These sounds are generally caused by thermal expansion or air blowing past a loose flap of metal. Once you locate where the sound is coming from, make a small dent in the metal. Be careful because this metal is usually very light. The dent should provide a more rigid and stable surface that is less likely to move as it heats. Contact a qualified technician if you do not feel comfortable dealing with the ductwork.