When we hear odd sounds coming from the hood of our cars, don’t we call our favorite mechanic? We rely on that expert to have our car humming again. A faulty furnace, too, makes noises signaling it may need a visit from a professional. What sounds will you hear from your furnace indicating it needs expert help?


This sound can indicate a motor or blower belt is loose or damaged. Dry shaft bearings or moving parts may also produce squeals. Contact an HVAC professional to tighten the belt and lubricate the parts.


Are you hearing a thumping or vibrating sound coming from your furnace? You may have a blower wheel or motor out of balance. An HVAC expert can diagnose the issue and restore balance before your furnace is damaged.


A dangerous gas buildup in your heating system can create a loud bang when you turn on your furnace. Immediately turn off the furnace and contact an HVAC professional to fix this potentially dangerous problem.

Bending of the metal siding of the furnace, prompted by undersized ducts, clogged filters, or closed vents may also cause a bang when the furnace turns on and off.


A metal-on-metal or scraping sound may signal a variety of problems with the furnace’s blower wheel. A loose blower wheel may scrape against the housing, and a broken one will vibrate and squeal in its housing.  If the motor mount is broken, it will allow the blower wheel to drop and also scrape against the housing. 


A furnace with a dirty gas burner or unadjusted pilot light makes a rumbling sound. A healthy furnace flame is blue; any other color of flame signals a problem. If your furnace is producing a rumbling sound or the furnace flame is not blue, immediately turn off the furnace and contact an HVAC professional.

Regular maintenance on our cars extends their usable lives, and routine maintenance of our furnaces ensures better performance from them, too. Listen carefully for sounds coming from your system; these sounds often signal a fault in your furnace. Contact an HVAC professional to do a thorough maintenance check on your system, remedy any issues, and ensure your furnace is humming again.