A/C belt melted off

Tiny
DEVILDOG25
  • MEMBER
  • 2001 NISSAN ALTIMA
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 180,000 MILES
I've changed my belts on my 2001 Nissan altima and the one that goes around the a/c compressor and the first time it melted it off and the second one it screechs and starts smoking, pulley is very hot and belts smoking and I'm not sure why?
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Monday, October 20th, 2014 AT 9:13 AM

7 Replies

Tiny
CARADIODOC
  • EXPERT
What you typed doesn't make sense, but if the belt is smoking, a pulley is locked up. Which one should be pretty easy to identify once the belt is removed.
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Monday, October 20th, 2014 AT 3:26 PM
Tiny
DEVILDOG25
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I've changed the idler pulley because the barings were busted but I was told to tighten it just snug enough you could turn it with no problems with your hand, but I put the belt and it spins but after a while it gets hot and makes a loud noise. Could it be the compressor?
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Monday, October 20th, 2014 AT 3:58 PM
Tiny
CARADIODOC
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There is no such thing as "tighten it just snug enough". No pulley is adjusted that way. Idler pulleys will have a bearing in the middle that needs to be clamped solidly by the bolt that goes through the center of it. If that bolt is loose, it can allow that pulley to turn or tip slightly. That will cause the belt to slide sideways across it as it goes around it, and that will generate a lot of heat, but it almost always sets up an irritating squeal too.

The AC compressor is typically not a likely suspect because you would have to have two separate problems. The clutch would have to be seized which would simply make the compressor run all the time, and the compressor would have to be locked up.
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Monday, October 20th, 2014 AT 4:07 PM
Tiny
DEVILDOG25
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Ok because my air works and bkiws cool air but the car makes a noise as if the pulley isn't on right.
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Monday, October 20th, 2014 AT 4:29 PM
Tiny
CARADIODOC
  • EXPERT
Try to sight down the pulleys from on top to see if there is one where the edge of the belt peeks out or is not perfectly inline with where it goes around the other pulleys. If you can see where the belt is running off-center, compared to the other pulleys, by as little as 1/16", that is enough to set up a squeal. This can be hard to do because moving your eyes just a little to either side can make the belt appear to be off. This works best when there are three pulleys that you can sight through, such as the crankshaft pulley, the generator or power steering pump on top, and an idler or tensioner pulley in between them.

The squealing almost always occurs where the smooth backside of the belt goes around an idler pulley. Squealing is less likely to occur where the ribbed side goes around a ribbed pulley. Ribbed pulleys are attached to things too that have relatively little tendency to tip or turn.
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Monday, October 20th, 2014 AT 5:05 PM
Tiny
DEVILDOG25
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The top one is fine its the bottom one that is squealing but it only does it if the a/c is on.
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Tuesday, October 21st, 2014 AT 9:49 AM
Tiny
CARADIODOC
  • EXPERT
Dandy. That narrows it down a lot. It looks like there's just the idler pulley and the AC compressor. The compressor pulley should spin very easily with one finger. In the front of it you'll see that metal disc with the three bolts in it. You should be able to turn that too but it is going to turn rather hard. The important thing is it will turn with no clunking or locking up. If that happens, the compressor will have to be replaced.

Next, look at that idler pulley. That one is usually adjustable to tighten the belt, and most of the time they are not spring-loaded like the other one. They have to have something loosened to allow it to be moved, then you make the adjustment, then tighten down whatever holds it in place. On some cars that means loosening that nut in the center of the pulley, adjusting it, then retightening that nut. If that nut is loose, it will allow the bearing and pulley to tip and will cause a squeal.
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Tuesday, October 21st, 2014 AT 11:15 PM

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