What Causes Abnormal Noise in Car Air Conditioning?
3 Answers
Here are the specific reasons for abnormal noise in car air conditioning: Dirty or stuck throttle valve: After the air conditioning is turned on, the compressor also starts working. Since the compressor is driven by the engine, turning on the air conditioning increases the engine load. The engine needs to increase the throttle valve opening to allow more air intake. When the throttle valve has carbon deposits or is stuck, it can cause engine vibration and abnormal noise. Air conditioning pump noise: There are two main reasons for air conditioning pump noise: the electromagnetic clutch and the bearings inside the air conditioning pump. Noise from the electromagnetic clutch is mainly caused by wear, which increases the gap. Noise from the air conditioning pump bearings is primarily due to a lack of lubricating oil. If these issues are not addressed promptly, the air conditioning pump can burn out, rendering the cooling system inoperable. Improper tension of the compressor drive belt: 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 tension of the drive belt can cause abnormal noise in mild cases and damage the air conditioning compressor in severe cases.
I remember that summer when I was driving, the car's AC suddenly started making a buzzing noise—it was incredibly annoying. I thought something might be stuck inside the blower fan, like a leaf or a small stone, which is pretty common. Later, when I took it to the repair shop, the mechanic said the fan bearings were worn out and needed replacement. Another possibility was that the compressor belt was loose or too old, causing a squeaky sound when running. If there was a refrigerant leak, unstable pressure could also produce strange noises, sounding like metal grinding. A clogged cabin air filter forces the fan to work harder, increasing the risk of noise. I usually recommend cleaning the AC intake regularly, especially during spring and autumn, to prevent debris from getting in. If the noise persists, it's best to visit a professional shop as soon as possible—don’t try fixing it yourself, as messing with the electrical system could make things worse. Honestly, I’ve dealt with weird AC noises several times, and each time, fixing it early saved me money and hassle.
Abnormal noises from the air conditioning while driving can be a real hazard, and I personally believe it should be prioritized for repair. The most common cause is a faulty blower—damaged fan blades or motor can result in buzzing or clicking sounds, directly reducing driving comfort and even affecting cooling efficiency, which is especially dangerous in hot weather. Another factor is a loose compressor belt, which can produce flapping noises while driving. If it suddenly snaps, the AC might stop working entirely, causing the windshield to fog up and obstructing visibility—particularly unsafe during rainy or snowy nights. Additionally, refrigerant leaks in the cooling system can lead to abnormal pressure, triggering whistling or metallic sounds, requiring inspection of pipe connections. I once encountered an abnormal noise that was resolved with just half an hour of simple maintenance—don’t delay minor issues, as prevention saves more money in the long run. Remember, safety comes first, and timely repairs are the most reliable solution.
