[z28barnett]

have a bad bearing in the A/C pulley. The system works fine but has a wine that sounds like a blower or a gear drive cam.

The clutch is not dragging and the sound is roughly halfed when I turn on the A/C and at its worst when it is off. My thought is the bearing in the pulley spins all of the time and with the clutch pulled in it side loads the bearing to quite it down some. I can hear the noise when turning the pulley by hand.

I have looked up the procedure in the GM shop manual. The clutch plate has to be pulled with a special tool. Then another tool is used to lock into the center of the pulley and pull the pulley off of the compressor shaft.

They list another set of tools to install the bearing and stake it in place and finally another tool to reinstall the pulley on the compressor.

They say that this can be done on the car without opening the A/C system.

Prices for the parts:

Bearing: $20.00

Tools: Not sure

Compressor with shippping: (New GM) $350

Receiver Dryer: (New GM) $50

New Clutch Pulley assembly: $110

My questions:

1) Has anyone done this job, are the special tools needed and where do you get them?

2). Is a functional 90K miles A/C compressor ready to be replaced anyway?

3). What do you think would be the most cost effective way to proceed?

Thanks

Z28

[z28barnett]

When the a/c clutch is disengaged, the outer part of the pulley is free-wheeling around the inner part, on a bearing. But when the clutch is engaged, that bearing is no longer rolling because the inner part starts turning too. So if it's still making the noise when the a/c is on, I think it's probably not that bearing.

If you have an idler pulley near it, it's probably changing the load on the idler pulley, and that's your most likely culprit. (easier to fix too) (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

A mechanics stethoscope should help you find which pulley exactly.

(or a length of garden hose or something similar...)

Just be careful not to get the hose caught up in a pulley or belt while you're checking around in there...

"When the a/c clutch is disengaged, the outer part of the pulley is free-wheeling around the inner part, on a bearing. But when the clutch is engaged, that bearing is no longer rolling because the inner part starts turning too. So if it's still making the noise when the a/c is on, I think it's probably not that bearing."

I thought the same thing, but if you look at a parts break down you will see that the pulley bearing doesn't press on to the shaft, it presses on to the nose of the compressor body. The bearing is spinning at all times A/C engaged or not. The compressor shaft floats in the center and has the outer clutch plate pressed on to it. When you start the compressor the pulley is then clutched to the compressor shaft. But the whole time the bearing was doing the same thing, inside race on the compressor body and outside race pressed into the ID of the pulley. The compresor is likely to have an internal shaft bearing, but that is not the one that I think is bad.

The tensioner was what I hoped it was but I pulled the belt and spun the tensioner pulley, no sound at all. Turned the compressor pulley and I could hear the dragging sound.

Thanks for the comments and for thaking the time to post.

Z28