# a/c compressor



## darrint (Feb 16, 2006)

I have a 99 frontier and every time I shut the truck off with the a/c on it makes a whining noise.It will also do it when I'm driving and I come to a stop.I just wondered what it was before I replaced the compressor.Thanks


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## dvdswanson (Nov 6, 2005)

have you had someone shut the truck off with you listening for where the whine is coming from?


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## SPEEDO (Jun 9, 2003)

it might be the tensioner pulley...


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## My98Front (Dec 31, 2006)

could be idler pulley, belt, or clutch bearing
I just changed my clutch bearing (about $12)
Run A/C and listen for squeak, turn off A/C, if squeak is gone it is your bearing.
How to change is another thread  
If not is probably one of the other two. Check belt tension and for wear such as cracks, if worn replace. Idler pulley check - Loosen belt and slip off of idler pulley, spin pulley by hand to see if pully is good.

Hope this helps,

My98Front


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## himilefrontier (Jan 21, 2003)

Could be the cycling switch is not cycling the compressor properly and is causing excess pressure to lock up the compressor leading to belt squeal. Happened on mine and killed the original compressor clutch and the replacement one before I figured it out.


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## Cusser (Apr 16, 2004)

Methinks I'd put on a new AC belt first, yours might be glazed some.


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## grrtt98 (Jul 28, 2004)

I can hear a squeaking sound when I see the AC clutch engage. I'm thinking about changing the bearing like My98Front suggested, but my repair manual only has instructions for the whole compressor. Can the clutch be removed without removing the entire compressor? Can I test the bearing by spinning the clutch with the belt off to be sure?


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## azrocketman (Oct 5, 2005)

grrtt98 said:


> I can hear a squeaking sound when I see the AC clutch engage. I'm thinking about changing the bearing like My98Front suggested, but my repair manual only has instructions for the whole compressor. Can the clutch be removed without removing the entire compressor? Can I test the bearing by spinning the clutch with the belt off to be sure?


Like Cusser recommended, I'd change the belt first. The belt is more likely to make noise when the driven pulley (the A/C compressor) is under load (clutch engaged).

Steve


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## Cusser (Apr 16, 2004)

grrtt98:
"I can hear a squeaking sound when I see the AC clutch engage. I'm thinking about changing the bearing like My98Front suggested." The bearing is functional when the AC is OFF; yes, you can remove the belt and spin it to listen/feel, but if the noise happens when the AC is ON (compressor clutch engaged), I'd change belts and tighten the belt well. To isolate, you could spray or brush on some belt dressing fluid to see if the noise disappears temporarily. "Can the clutch be removed without removing the entire compressor?" Yes, the clutch can be removed with the compressor in the truck (any vehicle) providing you have enough access to the front of the compressor. On my 4-cylinder 98 Frontier, the AC compressor is low on the engine...


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## grrtt98 (Jul 28, 2004)

Thanks for the posts guys. The noise I'm hearing occurs only as the clutch engages. It is not continuous, just a short chirp/squeak as the clutch comes under load. There is no noise at all at any other time whether the ac is on or off. It sounds a little more metallic than the belt slipping, but I'll check that first.


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## grrtt98 (Jul 28, 2004)

My noise was ceased by simply tightening the belt a little.


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