Is Sound An Issue In An HVAC Unit?

Is Sound An Issue In An HVAC Unit

While you may be used to the gentle hum of your HVAC unit when it's operating, there may be a few other sounds that can be alarming. Heating and cooling units can be loud. While they are considerably quieter than their older versions, they're still noisy enough to be placed outside. However, some sounds coming from your unit may indicate a problem.

A Gentle Hum

When your HVAC unit is running smoothly, you'll likely only hear a gentle humming sound when it clicks on. Sometimes, you might hear a brief pounding or clicking sound. This is merely the furnace or air conditioning unit turning on. It's not uncommon to hear air passing through your vents either. The volume of the hum or hissing is dependent upon the unit itself. Some brands are louder than others. If you only hear a humming or slight hissing sound, then your unit is likely operating just fine.

Metal Against Metal

The sounds that indicate a problem can be described as metal hitting against metal. If you hear this sound, then you need to turn off the unit immediately. In regards to the furnace, this sound could be a result of the blower having dislodged from its holder. It's hitting the sides of the AC unit as well as anything else. Because this can cause further problems for the unit, it's best to have an HVAC professional examine the unit before it's turned back on.


Another sound that might indicate a problem is a thumping. Again, this might be because a band, a wheel, or some other part has fallen off and is hitting the inside of the unit. This can be true of the furnace as well. Take a listen to the thumping. If it's consistent and wasn't noticed originally, then something is likely wrong. Turn off the unit and contact an HVAC professional take a look at it.


Sometimes, you can hear a tiny vibrating noise. You may even find that the unit itself is vibrating. Some units just vibrate and make this noise. It's not a bad idea to ask the installer if vibrating is expected. However, if it starts to vibrate too much, then this might indicate a problem. The indoor fan or the capacitor could have an issue.


When your unit kicks on, you may notice a popping or banging sound. This noise may occur again when the unit shuts down. This is typically due to the negative pressure inside of the unit caused by a clogged filter or duct that's flimsy.

Loud noises can be the first sign that your unit is in trouble. If you are unsure or hear something troubling, then call us today at (903) 597-8381 to schedule for maintenance with our HVAC professional.