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4 Weird AC Sounds and What They Could Mean


It can be alarming for your air conditioner to begin making unusual sounds. You know that something is wrong, you just don’t know what. If you hear any of these four weird AC sounds, you need to give our team a call for an air conditioning tune-up in Burlington, VT.

You may be tempted to ignore any usual sounds in hopes that they go away on their own. However, this rarely happens. Instead, issues can worsen and put strain on other areas of your air conditioner. Keep reading to learn about why these four sounds are bad news for your air conditioner. 


There are a variety of problems that can lead to buzzing in your AC. One of the most common that we see is loose isolation feet. Your air compressor sits on a set of isolation feet to keep it slightly up off of the surface. As time goes on, these isolation feet can shift around or break, resulting in a buzzing sound. 


This sound is usually described as metal on metal. Some people may also describe it as shrieking or screaming. It usually originates in one of the motors in your AC. For example, your fan motor or the compressor motor may lack lubrication or have something that is off-center. 

As a result, motor parts are making a loud noise as they bang together. When you hear a shrieking or screeching AC sound you need to turn your air conditioner off right away and give us a call. Allowing the sound to continue could damage your motor beyond repair. 


If you hear a quiet, gentle humming as your compressor works, that is completely normal. But if the humming gets louder, that is a problem. When your thermostat signals for your air conditioner to come on, there is a contactor relay switch that communicates with the compressor. 

If you hear an unusual humming sound, it may be because of a defect with this switch. It’s a strong indication that there is some type of electrical problem, so you need to get it checked out right away. Otherwise, you could face a fire hazard or cause more damage to your air conditioner.  

Rattling or Banging

When you hear a rattling sound in your AC, that means smaller parts are loose and moving around. Sometimes, debris can get in the outdoor portion of your unit. Other times there are loose screws and other small parts inside moving around. A louder banging sound can mean a larger part is loose. 

It may not be moving around your air conditioner, but it’s loose enough to knock against a side or another AC component. Either way, it’s usually a quick fix if the problem is caught early. The part in question can be tightened or replaced, and your air conditioner will be as good as new again. But, if it’s left unattended, the rattling or banging could lead to more extensive damage.

Red Rock Mechanical, LLC serves Northwest Vermont and Northeast New York. Schedule AC service with us today.

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