Troubleshooting Common Furnace Noises

Posted on: 11 February 2019


When your central forced air furnace kicks into gear, a certain amount of noise is to be expected, since the fan and blower system have to move a great deal of air through the ductwork and to the various rooms throughout your home. However, there are a few different sounds that can point to mechanical issues with your furnace. Knowing what the most common irregular sounds that your furnace can make are, and what issues they indicate, can help you identify problems quickly so that they can be addressed by a HVAC professional before they grow to be serious and expensive to fix.


Any high pitched sounds resembling a scream or screech coming out of your vents when your furnace turns on points to some sort of damage to the motor of the fan. A lack of lubrication or a worn piece of metal that is rubbing against another piece of metal is usually what will create this sort of sound. While your system will be able to function even if this is the case, it's a good idea to have a professional inspect the fan's motor, since running it without proper lubrication or with parts that have slipped out of place can greatly increase the amount of wear that the fan experiences, making failure much more likely.


In a similar line to the above point, you may hear a scraping sound coming out of your furnace if your blower wheel has become loose, coming into contact with another nearby metal component. In some cases, the scraping sound will take on a lower, constant humming sound, but both types of noises indicate that your blower is experiencing excessive wear and is at risk of burning out completely or damaging other parts of your furnace. Avoid running your furnace at all until a professional has had a chance to inspect the blower casing.

Popping or Snapping

A popping or snapping sound, especially if it is happening at a fairly regular interval, indicates that your ducts have become damaged. As ducts are exposed to both hot and cold air throughout the year, they can expand and contract. This places strain on the fasteners that connect individual sections of your ductwork together. Eventually, it becomes possible for a section of ductwork to snap out of place, and will snap or pop as air passes by it. If this is the case, your ductwork will be leaking heat, which can lead to higher energy bills and uneven temperatures in your home so you should have your ducts inspected and repaired as soon as possible.

Contact a furnace repair service for more help.