3 Noises You May Be Hearing From Your HVAC Unit And What They Mean

Posted on: 12 November 2014

When a healthy HVAC unit is running, you should not hear any sounds coming from it except for the sound of air blowing through your vents. When you start hearing noises that are not normal, this tells you something is wrong. Below are three sounds you may be hearing and what they mean:

Loud Banging

A loud banging sound is likely coming from the fan that is inside the unit. It could also be due to the shaft rotating it. Fortunately, this is a problem you may be able to fix yourself.

Turn the HVAC unit off first to prevent it from further damage, and then check the top of it for any debris, such as branches, leaves, etc.  If you find any debris, it will obstruct the fan and keep it from turning on. If you do not find any debris, you can open the unit and look at the shaft. Refer to the user's manual on how to open your particular unit.

The shaft is located right below the fan. If it appears to be loose, you can tighten it up, and see if the noise is gone. If you still hear it, the shaft could be broken, and will need to be repaired or replaced.

Squealing or Chirping Sound

If you are hearing a chirping or squealing sound coming from your HVAC unit, this may be due to two parts rubbing together without being properly lubricated. Over time, the lubrication wears away, and all parts will need to be lubricated again.

It can also be due to an outdoor condenser or fan that is close to breaking. Turn off the unit immediately, and do not turn it back on until the problem is fixed. If this problem is not fixed, it can cause further damage to your unit, which will result in a larger repair bill.

Vibration and Rattling

HVAC units use a type of isolation padding that absorbs the noise produced by the internal parts. If these pads are worn out or broken, this will increase the sounds your unit makes.

If you hear a rattling noise when air is blowing through the system, it could be a problem with the fan or motor wheel.

Call a HVAC repair technician when you start hearing sounds coming from your HVAC unit. Telling them the sounds you are hearing can help them diagnose the problem  with your heating and cooling system quicker, and get it back up and running for you.