What is the reason for the belt noise when the air conditioner is turned on but stops after a while?
4 Answers
If the belt makes noise when the air conditioner is turned on but stops after a while, it may be caused by belt slippage. Here are detailed explanations on how to resolve belt noise issues: 1. Check the belt: Inspect whether the driven accessories have bearing damage, jamming, looseness, or increased power demand. 2. Replace the belt: This type of noise is often caused by the contact surfaces between the belt and pulley becoming too smooth. Replace the belt or use 100-grit sandpaper to roughen the contact surfaces of the pulley and belt. 3. Temporary solution: You can apply 1-2 drops of engine oil to the contact surfaces between the belt and pulley.
In my many years of car repair experience, I've encountered numerous car owners complaining about squeaky belts after turning on the AC, which usually stops after a while. This is typically caused by belt slippage. When the AC starts, the compressor adds extra load to the engine, causing loose belts to temporarily slip and produce annoying noises. After running for a while, the belt tightens due to heat expansion and contraction from the engine, restoring friction and naturally eliminating the noise. Another common cause is aging or worn belts, where surface cracks lead to initial slippage that quiets down after heating up during operation. Don't underestimate this small signal—I've seen many cases where ignoring it eventually led to belt breakage, AC failure, and compromised driving safety. I recommend promptly visiting a repair shop to check belt tension, with normal values typically ranging between 800-1000 Newtons. Loose belts should be adjusted or replaced entirely to prevent more significant failures. Regular maintenance of the belt system during routine servicing can extend component lifespan and ensure driving comfort.
As a young driver, I've also experienced the annoying squealing sound from the belt when the AC is first turned on, which stops after a while. I asked a car-savvy friend, who explained that when the AC compressor starts, the sudden increase in load can cause the belt to slip and make noise if it's too loose or dirty—just like how loose shoelaces drag when walking. After running for a few minutes, the belt heats up and dries out, gripping better and stopping the noise. But don't take it lightly—my car's belt had this issue and soon cracked, costing a lot to repair. I suggest checking it yourself when you have time: pop the hood and inspect the belt for wear. If you see cracks or it feels loose, get it fixed at a repair shop ASAP. Also, reducing frequent AC on/off cycles while driving helps minimize belt stress and prevents minor issues from escalating. Keeping the engine bay clean and dust-free can also extend the belt's lifespan.
Our family car often makes a few squealing noises from the belt when the AC is turned on, then stops. Simply put, it's caused by belt slippage. When the AC starts, the load increases, and a loose belt rubs against the pulley, making noise. The noise stops once the belt heats up and expands, eliminating the slip. My husband warned me to pay attention to this because aged belts are prone to snapping, which could affect AC cooling. Now during every maintenance, I remind the technician to check the belt tension—if it's loose, it needs tightening. Don't delay; addressing minor noises can prevent major breakdowns.
