What Causes the Abnormal Noise When Turning on the AC Button?

[ZacharyLee]

Here are the specific reasons for the abnormal noise when turning on the AC button in a car: 1. Contaminated electromagnetic clutch: Due to the electromagnetic clutch being located relatively close to the ground, prolonged driving can cause it to accumulate dirt or mud, leading to bearing damage and resulting in abnormal noise. 2. Loose drive belt: The car's air conditioning compressor places high demands on the electromagnetic clutch during operation. A loose drive belt increases the load on the electromagnetic clutch, making it prone to damage and, in severe cases, causing the compressor to burn out. 3. Repeated engagement of the electromagnetic clutch: Frequent engagement of the electromagnetic clutch can lead to insufficient power generation from the alternator, causing the compressor to operate with inadequate voltage and resulting in abnormal noise. 4. Lack of lubricating oil: Insufficient lubricating oil inside the compressor. After prolonged use, it's necessary to add an appropriate amount of lubricating oil to avoid abnormal noise or failure due to friction.

[McKing]

I've been driving for over a decade and encountered this issue several times. When you press the AC button and hear strange noises, it's mostly because of the sound made by the air conditioning compressor when it starts up. There's a clutch inside the compressor, and if it's slightly stuck or loose when engaging, it can produce squeaking or humming sounds. Another possibility is a problem with the belt. That belt connects the engine and the compressor, and if it's aged, too tight, or loose, friction noises can occur. If the blower fan is clogged with dust or the blades are slipping, it's also prone to making noise when the AC is turned on. I recommend opening the hood and trying the AC while the car is idling to listen for where the sound is coming from. If it's just a simple belt noise, you can tighten it or clean out debris yourself. But if the compressor is making strange noises, you should take it to a repair shop for inspection. Don't delay dealing with it. Over time, not only will the AC stop cooling properly, but it may also increase fuel consumption and make driving less comfortable.

[AliceMarie]

As a DIY car repair enthusiast, I find this sound quite common. The abnormal noise when pressing the AC button typically comes from two possible sources: First, mechanical parts within the air conditioning system, such as the vibration sound when the compressor solenoid valve engages, or the fan bearing wear causing uneven rotation. Second, external transmission issues, like a loose drive belt slipping and producing a squeak during startup. You can start with a simple check: Open the engine compartment, start the car, and turn on the AC to see if the belt pulley wobbles excessively. If the belt seems fine, then listen to the compressor's operation—continuous noise is normal, but sudden clunking or screeching sounds should raise concern, possibly indicating insufficient refrigerant causing dry friction in components. Addressing it promptly can prevent minor issues from turning into major repairs and maintain cabin comfort.

[Sauron]

This situation sounds quite concerning, safety first. When you press the AC button and hear strange noises, common causes include a faulty starter device in the air conditioning compressor or a slipping belt, producing clicking or squeaking sounds. If the compressor is excessively worn and operates unevenly, the noise becomes louder; an aged or misaligned belt can also create friction noises upon startup. More importantly, ignoring this issue may lead to reduced AC efficiency, obstructed visibility or distraction while driving in hot weather, posing significant safety risks. It is recommended to promptly check if the pulley and fasteners are loose, and consult a professional if necessary. Addressing the issue early not only saves trouble but also ensures a stable in-car environment.