Whiring & Whining sound on my 2003 Envoy 170KM

I've been waiting for the whiring/whining sound to get worse, and it has, but I still can't isolate the cause. Thanks to the tips here: I have removed the idler pulley and its ok; I have felt the tensioner pulley it it feels and sounds ok; I've flushed and replaced the PS fluid and it hasn't made a difference nor does turning the wheels; the water pump seems ok; I removed the alternator and it checks out ok, and: the belt looks healthy. A stethoscope wasn't much help, although if I had to guess, I'd say the sound is the loudest on the drivers side.

So, I sure would appreciate hearing your ideas - I suspect the front A/C bearing but dread the cost and complexity of repair. Pretty hard to tell here in winter, but think the sound is actually quieter when teh AC is on. Does anyone have any experience changing the bearing while the unit remains in the truck?

Thank you.

So it is in the accessories, no noise with the belt off?

No noise with belt off!

Ok, try turning the ac pulley and water pump to se if you can feel a bad bearing, if not listen to these units belt on using a mechanics stethoscope.

OK, I removed the belt again and as before the whiring sound stopped. The waterpump seemed tight when spun by hand noise free. With no belt, the AC front unit (the one that drives the compressor I think) also spun tight and noise free. The AC unit that the belt rides on felt a little loose and made a rumbling sound when spun by hand (kinda like the noise you'd hear when you manually spin an old brake drum as it touches the worn shoes). With the belt back on and running, the stethoscope picked up the loudest sound near the AC unit and pipes. I must say though, it sounded more like a mechanical noise rather than the whiring/whining sound I hear without the stethoscope.

To be thorough, I went back to the power steering reservoir and discovered the fluid was quite dark and contaminated (as before). I sucked out and replaced about 1/2 litre and added some Lucas goop and the sound appeared to diminish.

I'm beginning to think I may have two problems and perhaps should wait a little longer for the sound(s) to get a little worse. I also suspect I need to do a more thorough job of replacing the PS fluid.

Thanks Max.

10-15 turkey baster flushes of the PS fluid reduced the whiring/whining noise to an acceptable level. Next, I'm sure I'll have to deal with the A/C compressor front bearing noise.

Last post: the PS noise is still fine.

As for the A/C compressor noise, I found an NSK front bearing (TRSBG) on Ebay for $17 and had a local garage install it without removing the compressor or discharging the system. The tough job was made even more difficult due to the bearing race having been 'spot pinned' in place. I was very pleased with the $200 repair cost (Cdn$).

All quiet now.

Good deal, thanks for posting the results.