What Is That Car Air Conditioner Squealing Noise?

What Is That Car Air Conditioner Squealing Noise

No one wants to get in their car and hear that dreaded car air conditioner squealing noise. It can quickly lead to anxiety and a trail of questions.

Why is my car AC making this noise? How much longer will my AC last? Is my car falling apart? How much money will this cost me?

Luckily, there’s good news. Not all car AC noises indicate trouble under the hood.

We’ve created a simple guide to the noises your air conditioner might be making. However, if you’re ever in doubt, it’s always wise to seek out a professional at Colony One Auto Center in Sugar Land or Stafford.

Squealing car AC and other common noises


Does your car make a squealing noise when the AC is turned on? If it does, you’re not alone. This is the most common “weird car sound” customers call into the shop.

In most cases, a squealing car air conditioner noise is caused by a worn out serpentine belt.

The serpentine belt is a long, winding belt that keeps many crucial parts of your car functioning, including the power steering pump, air pump, water pump, alternator, and (of course) your air conditioner.

With correct tensioning and proper maintenance, serpentine belts are built to last between 50,000 and 100,000 miles. That said, these sturdy, hardworking belts occasionally need to be replaced.

If you want to test whether your serpentine belt is the culprit behind the squealing noises emanating from your car’s AC, fill a spray bottle with water and spray down the belt. If the squealing noise disappears, you should take your car into the shop and request further inspection.

Knocking and clicking

Knocking and clicking noises coming for a car’s AC isn’t as common as squealing, but it does happen.

Knocking and clicking noises can occur if the mounting bolts that hold AC components in place are too loose or if the compressor is in bad shape internally. Tightening and adding some thread-locking compound to the bolts should take care of the noise if it’s amounting issue and not an internal one. It’s a rather simple and inexpensive fix.


If you turn on your air conditioner and it makes a buzzing noise, chances are that your AC compressor is in distress. Specifically, it’s likely “overcharged,” meaning that too much Freon has been added to the system.

If you suspect that your AC compressor is overcharged, take your car in immediately. The buzzing occurs when the refrigerant enters the compressor intake port, which can cause a lot of damage to your car.

Replacing an AC compressor requires the help of a professional and can often be an expensive repair.

Normal air conditioning noises


Say you’ve been out running errands on a hot summer day in Texas. At some point, you park and turn off your car — only to hear a hissing noise coming from your AC.

It’s important not to panic. A hissing AC system is not only normal but good.

Your car’s AC system has two sides separated by a valve or tube. These sides contain Freon at either a high or low pressure. When you turn off your car, the Freon from the high-pressure side seeps back into the low-pressure side, ultimately creating a hissing noise.

Is your car making unusual noises?

When you’re on the road and you hear the dreaded car air conditioner squealing noise — or any other unfamiliar noise — the smartest thing to do is to have your car inspected.

The professionals of Colony One Auto Center in Sugar Land and Stafford are available from 7am-6pm, Monday through Friday for all of your vehicle service and inspection needs. We have over 25 years of experience diagnosing and repairing any and all “weird car noises.”

Call us at (281) 980-4440, stop by our Sugar Land or Stafford locations, or request a service online today.