3 Reasons Your Car's A/C Compressor Makes Strange Noises

Posted on: 5 July 2018

It only takes a sweltering summer day to make you thankful for your car's air conditioning. When you start hearing strange noises every time you use your A/C system, there's plenty of reason to be worried. These noises could indicate the beginning of compressor failure, which could rob you of your air conditioning and cost you hundreds or even thousands of dollars in repairs.

If your car's A/C compressor starts making a racket, it's likely due to the problems listed below. Read on to find out how you can tackle these issues.

1. Too Much Refrigerant

Your A/C system is designed to only hold a certain amount of refrigerant. If too much is added, the excess refrigerant could be drawn into the compressor's intake port. Not only does this cause a buzzing sound in the compressor, but it could also lead to severe compressor damage and eventual failure. An overcharged air conditioner will also fail to cool properly.

Fortunately, this problem can be corrected early on by having your technician fill the air conditioning system with the correct amount of refrigerant. Otherwise, you can look forward to a failed compressor and an expensive repair.

2. Worn Bearings

If you hear a grinding, squealing, or roaring noise, then chances are your compressor pulley's bearings are shot. To make certain of this, remove the serpentine or A/C compressor belt and rotate each pulley to isolate and pinpoint the source of the noise.

Replacing the compressor pulley bearings can be an involving job that requires special tools to complete. In most cases, you're better off purchasing a brand-new or remanufactured compressor.

3. Loose Mounting Bolts

Mounting bolts that were improperly tightened can also cause the compressor to move around during operation. When this happens, you'll likely hear knocking or constant clicking sounds from under the hood. To diagnose this problem, all you have to do is look inside engine bay and watch the A/C compressor for any signs of excessive movement.

Simply tightening the bolts or torquing them back to their manufacturer-recommended specs can help stop the shaking and vibrations. To keep the bolts from moving back out, remove the bolt and add a small amount of thread-locking compound on the last few threads before reinserting and tightening the bolt.

Keep in mind that rattling noises during A/C compressor operation can also be caused by a worn compressor clutch. On some makes, the compressor clutch can be replaced without replacing the entire compressor. 

To make sure your vehicle is running properly, look into getting a car A/C inspection.