How to Solve the Issue of Abnormal Noise When Accelerating with AC On but Not When Off?
3 Answers
Listen carefully near the glove box on the passenger side. If you hear a sound similar to flowing water, this is the expansion valve of the AC working, which is a normal phenomenon. Remove the glove box cover and take out the AC filter. Then, start the engine, turn on the AC, and set it to the maximum fan speed to blow out any foreign objects in the air ducts. Use a pressure gauge to check the pressure in the entire AC system. Abnormal pressure, whether too high or too low, can cause noise. Adjust it to the appropriate level. Inspect the electromagnetic clutch of the AC compressor to see if it is making proper contact or if there is any short circuit or open circuit. Replace the clutch if necessary.
Last time my own car had this issue too - when I turned on the AC and stepped on the gas, there was this squeaky noise, but it went away immediately after turning off the AC. After struggling for a while, I found out it was because the AC compressor belt was loose. When belts age and become slack, the increased load from compressor startup causes the belt to slip and make friction noise when revving the engine. You need to check the belt's condition - look for cracks or excessive wear. Also need to inspect if the tensioner pulley is stuck or malfunctioning. Replacing the belt isn't too expensive, but pay attention to model matching. Some cars even require removing protective covers to access it. Remember to pay attention to engine bay sound changes during daily use, especially during summer when AC is used frequently - that's when this problem most commonly occurs. If you're handy, you can try adjusting the tension yourself, but for belt replacement it's recommended to visit an auto repair shop for more reliable service, since the location can be tricky to work on.
Abnormal noise when accelerating with AC on is mostly caused by issues with the AC compressor's drive components. Prioritize checking the belt system: The AC compressor is driven by a belt, and belt slippage can produce sharp noises; a faulty tensioner pulley bearing may cause a humming sound. Slippage in the compressor clutch can also trigger abnormal noises. For self-inspection, open the engine hood, start the engine, and have someone press the accelerator while you carefully listen for the noise source. Observe if the belt vibrates noticeably and use a flashlight to check if the tensioner pulley rotates smoothly (remember not to touch any parts while the engine is running). These components are prone to aging in the high-temperature engine compartment, especially in vehicles six or seven years old. If the belt's inner side has a shiny, mirror-like gloss, it's time for a replacement. Repair costs vary by vehicle model: for regular cars, belt replacement costs under 200 yuan, while replacing the tensioner pulley assembly may cost around 300-400 yuan.
