What Causes the Squeaking Noise from the Car Air Conditioning Compressor Belt?

[Michelle]

The electromagnetic clutch of the compressor is a common source of abnormal noise: The compressor frequently operates under high load conditions, transitioning from low to high speeds, which places high demands on the electromagnetic clutch. Additionally, the electromagnetic clutch is usually installed close to the ground and often comes into contact with rain and mud. When the bearings inside the electromagnetic clutch are damaged, abnormal noise occurs. The solution is to repair the bearings of the electromagnetic clutch. The tightness of the compressor drive belt also directly affects the lifespan of the electromagnetic clutch, leading to abnormal noise: If the drive belt is too loose, the electromagnetic clutch is prone to slipping. If the drive belt is too tight, the load on the electromagnetic clutch increases. Improper belt tightness can cause the compressor to stop working in mild cases or lead to compressor damage in severe cases. When the drive belt is operating, if the compressor pulley and the generator pulley are not aligned in the same plane, it can reduce the lifespan of the drive belt or the compressor. The solution is to adjust the tightness of the compressor drive belt.

[DeVivienne]

I've been driving for decades and often encounter squealing noises from the air conditioning compressor belt, mostly due to belt looseness or excessive wear. When the belt ages and hardens, it slips against the pulley during rotation, causing noise, which is more noticeable in rainy weather because moisture increases slippage. Problems with the compressor, such as a bad bearing or an uneven pulley surface, can also cause uneven load and louder noise. I've tried adjusting the tension myself in the past and used soapy water as a temporary fix. If the belt is about to break, it must be replaced—normally every 50,000 to 100,000 kilometers. If not addressed in time, a broken belt will stop the air conditioning completely, making summer driving unbearably hot. It's advisable to regularly check the belt tension and have it replaced by a professional shop with a high-quality belt for peace of mind. From my experience, it's a minor issue that can easily escalate into a major problem, so fixing it early saves both hassle and money.

[SanClara]

As a car-savvy buddy, the squeaking noise from the compressor belt is mainly caused by slipping. The primary reasons are either the belt being too loose (causing slippage) or too tight (increasing wear). Contamination with oil or moisture on the surface can also make the noise more pronounced. Compressor faults, such as bearing damage or pulley deformation, can lead to uneven rotation and amplify the noise. During inspection, first turn off the engine and check the belt tension—it should be normal if you can press it slightly with your fingers. Don’t ignore minor squeaks, as they can accelerate belt aging or even lead to breakage, causing the AC to fail. It’s recommended to inspect the belt every 30,000 km and use specialized cleaners for stains. If replacing the belt, opt for high-quality materials to prevent recurring issues, and also check the idler pulley or tensioner. Safety comes first—don’t drive with a faulty belt, as it affects comfort.

[VonTalia]

My car made the same squeaking noise last time, and the mechanic said it was due to worn and loose belts. It's especially noticeable on rainy days because the belts slip more. Upon inspection, we found oil stains on the surface, and it got better after cleaning. Reminder: belts generally have a lifespan of about 6 years, and they lose elasticity and become noisy as they age. Replacing the new belt solved the problem. Usually, pay attention to keeping the engine compartment clean to avoid dust and water accumulation, which can reduce noise. Check the belt condition yourself to see if there are many cracks. Fix any issues promptly to avoid sudden belt breakage and air conditioning failure.