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Yost & Campbell Heating, Cooling & Generators Blog

5 Sounds an AC Should Not Be Making

Homeowners can usually tell when there’s something wrong with an AC unit, just by the way of the noises they make. A central air conditioner that’s functioning properly shouldn’t make any noises aside from the gentle waft of a refreshing breeze coming from air ducts. However, if an air conditioner is making some peculiar noise, this is often a clue towards a problem that’s much bigger in scale. Sometimes there are even home solutions for AC repair in Harrison, NY, if they’re appropriately addressed with the right tools.

There’s got to be a way to classify these issues by sound and inform homeowners on just how pertinent they should be about an AC that sounds “off.” This list of air conditioner sounds is pretty well known throughout the HVAC industry. It’s not okay to just sit back and pretend that an air conditioner is supposed to make these noises.

So, what kinds of noises are we talking about?

Bubbling or Hissing

A bubbling or hissing noise is usually a clue towards a refrigerant leak. Refrigerant is kept in an air conditioner under high pressure as either a gas or a liquid. When this escapes the system, which is a severe problem if it does, it usually rings out with a hissing or bubbling sound that signifies gas or liquid interacting with air.

Whining or Whistling

Just like when people whistle using their mouths, whistling signifies restricted airflow at some point in the unit. This could mean an airflow problem at a variety of locations. For instance, this could be a signal of incompatible or broken air ducts, clogged filters, or a different location where air flows. If the noise goes away after replacing the air filter, then the problem is solved!

Shaking or Rattling

Contrary to what some people would like to believe, an air conditioner is still a high tech piece of machinery. When screws, motors, or parts of the air ducts become loose, they begin to rattle and shake violently. This can get more damaging over time, and usually needs to be repaired as soon as possible.


A buzzing noise is usually a sign that there is an electrical problem with the unit. Just like the noise of a light bulb or computer working too hard, or the zap of an electrical current, air conditioners begin to buzz when they run into electrical difficulty.

Humming Noise

Humming noises can sometimes indicate a worn-out fan. When these fans wear down, the blades shift quite a ways from where they initially started. That means they’ll gently brush against other material in the air conditioner, causing a gentle (yet obnoxious) humming noise.

These problems sometimes can be fixed with a changed air filter or a tightened screw. However, when unsure, they should always be addressed by a professional technician. These issues can often deal with hazardous chemicals like refrigerant or dangerous electrical systems contained within an air conditioner.

Still have a question about AC noises? Contact Yost & Campbell Heating, Cooling & Generators.

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