What’s That Noise? Diagnosing HVAC Sounds

On a hot summer day, the neighborhood is filled with a constant hum as everyone stays indoors trying to cool off in front of the A/C.  But what happens when things get noisier? Separating the common buzz from an unusual clank can be difficult. If you find yourself wondering, “Is that sound normal?,” this will help you learn what to listen for.

  1. Squeaking or screeching: Squealing noises from the blower motor can be a sign of a bad belt. Belts should be replaced before they break to avoid further damage.

  2. Clicking: It’s normal to hear a bit of clicking, especially after you have turned your unit off. But if you hear repeated clicks from your outside compressor, your relay might be defective. In some cases, an electrical control might be the cause of your relay to timeout and fail.

  3. Rattling: Ahh, the dreaded rattling noise. When it comes to turning on your compressor unit, a rattling noise is an indication that there could possibly loose hardware or a failing motor. The louder the sound, the more serious it usually is.

  4. Banging: Hearing banging sounds when the blower is running is never a good sign. Typically, this is a warning that something has broken or disconnected and at this point the system should be turned off.

  5. Thwaping: You know the noise you hear when a playing card is placed in the spoke of a bicycle? This is the same noise you’ll often hear if something is stuck in the blower blades of your unit. This is not dangerous, but should be addressed quickly as the debris creating resistance can make the motor burn out extremely fast.


Hearing an unusual noise coming from your air conditioner? We recommend turning off your A/C to avoid further damage and give the professionals at A.B. May a call! Our 24/7 emergency service will ensure that you never go a day without your A/C. To schedule service give us a call at 913-370-4898 today!