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Q: My car is making a squealing sound when it cranks and when I turn on the A/C

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Hi, I have a 2009 Hyundai Elantra and my car squeals really loud when I first crank up, the car does settles after a couple minutes. If I try to drive while the car is squealing, it gets even louder. Also, my car squeals when I turn on the A/C. Do you know what could possibly be my problem? I have recently gotten a new alternator belt. Also, I think that possibly a bolt or something could be missing or loose, based on what one mechanic told me.

My car has 100000 miles.
My car has an automatic transmission.

Hi, thanks for writing in. What you’re describing sounds a lot like an AC belt that is loose or the serpentine belt on your alternator loose (or a combination of both). A common mistake that some mechanics make is not properly tightening the alternator after replacing the belts. The fact that the previous mechanic indicated that there may be a bolt missing also raises a red flag to me that the alternator might be a problem.

However, you mentioned also that the car squeals when you turn on the AC and that it gets louder as you drive. When a belt is loose it creates a harmonic squeal, and as the belt moves faster (when you accelerate) it progressively gets worse.

I think the best thing you can do is to find a another mechanic that can fully inspect your alternator and AC belts, replace any lost nuts or bolts on your current alternator, and get rid of that annoying squealing sound. A certified technician from YourMechanic can come to your home or office to inspect you AC squeal and let you know exactly what needs to be done.

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