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Q: Rattling from AC when idling

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I can hear a rattling noise in the engine compartment when I engage the air conditioner. The air conditioner still works. The rattling sound occurs while idling at stop lights.

A: The rattling may be from the AC compressor ...

The rattling may be from the AC compressor pulley or tensioner for the belt. The tensioner is the most common problem, but the spring may be too weak causing vibrations and rattles. I recommend seeking a mechanic, such as one from YourMechanic, to come and test your vehicle for you. They will be able to diagnose the car noise and replace the belt tensioner if necessary.

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