What Causes Abnormal Noise in Car Air Conditioners?

[Hylla]

Reasons for abnormal noise in car air conditioners: 1. Lack of lubricating refrigerant oil inside the compressor, causing metal friction sounds when the compressor's electromagnetic clutch engages. 2. Abnormal noise due to excessive tension on the air conditioning belt. 3. Faulty electromagnetic clutch, with damaged internal bearings producing abnormal noise. The following is an introduction to the car air conditioning system: The car air conditioning system is a device that cools, heats, ventilates, and purifies the air inside the vehicle. It includes cooling devices, heating devices, and ventilation devices. This combined system makes full use of the limited space inside the car, with a simple structure that is easy to operate. The air conditioning system can provide a comfortable environment for passengers and reduce driver fatigue.

[VincentRose]

Last time I encountered strange noises from the AC, it took me a long time to figure it out. Now I'm sharing my experience to help others avoid detours. The most common issue is the blower motor malfunction—either loose fan blades or debris inside, like leaves getting stuck causing a rattling sound. You can see this by removing the glove box. Another issue is belt aging, especially when the AC squeals upon startup—80% chance it's the compressor belt being loose or worn/cracked. The sound of belt slippage is particularly noticeable. Refrigerant problems can also cause gurgling noises; if cooling performance is poor accompanied by strange sounds, check the pipelines. Oh, and compressor bearing failure is the most troublesome—produces a deep humming noise. This needs immediate repair or it might burn out the entire AC system. Loose chassis components like brackets can also transmit noises into the cabin. Get a friend to listen outside the car for more accurate diagnosis.

[Eileen]

Hey, the car AC makes annoying noises as soon as it's turned on! I've researched the main causes. The blower motor is the most common culprit—lack of lubrication in the bearings or deformed fan blades can cause a buzzing sound. If the noise persists even when you turn off the AC and just run the fan, that confirms it's the blower motor. As for the compressor, a loose belt can produce a sharp screeching sound—just pop the hood and check the belt tension. If the compressor itself makes a rattling noise, it’s likely due to worn bearings or piston issues inside. Don’t ignore a gurgling sound either—it could indicate refrigerant leakage or a clogged line, especially if the dashboard warning light stays on. A dirty air filter can also strain the blower and cause unusual noises, but replacing it yourself takes just five minutes. Bottom line: strange noises are the AC’s way of sounding the alarm—fix it early to save money!