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Q: AC making loud noise when on

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I recently had the AC compressor replaced. The car is making a loud noise when the AC is on. I think the AC compressor belt might need adjusting. It stops when I turn the AC off and leave just the fan running.

Hello, your Subaru has a serpentine belt with an automatic adjuster and the noise with AC on indicates there is a problem with the compressor, not the compressor clutch. Since you just replaced the compressor, it may be that the AC system is overcharged making the compressor hard to turn. Because the noise goes away when you turn off the AC, then it indicates that the compressor clutch is functioning normally. It is also possible the compressor itself is defective. I would suggest returning to the technician/shop that did the installation of the new compressor to repair these problems for you.

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