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Q: Loud air conditioner noise

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My car has been driving fine. I turned on my ac yesterday and heard a weird noise.. first sounded like a loud humming noise then a clanking sound. I stopped and turned the ac off and the car was fine. Turned it back on and the noise was back. Any ideas what this noise could be coming from?

My car has 200000 miles.
My car has an automatic transmission.

Do you hear the noise with the engine running and A/C off as well? If not, your problem may be the A/C compressor clutch or the bearings in the belt driven compressor pulley. If you always hear the noise while the engine is running, the problem may be another component in the belt drive system and turning on the A/C makes the noise louder. While the engine is cool, take a look under the hood with a flashlight and check your fluid levels. Consider hiring an experienced technician like one from YourMechanic to take a close look at the vehicle and offer a personal diagnosis.

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