Grinding,screeching noise stop when AC is turned OFF !!??

1999 LeSabre 3800 Series 2
AC works fine, no noise when in use.
When AC is shut off , we hear this loud , screeching , grinding , wailing , scrunching, high pitched noise.

Not sure what to check? Should I apply a lube to the belt,pulley, etc

??:runaround::runaround:

This sounds like classic v-5 clutch drag- the compressor clutch air gap has tightened and needs to be adjusted back to .020" . I have answered this several times- and usually see about 1 a week during the hot season. The noise is a scrapping/rattle only with a/c off- should see signs of metal shavings about the clutch hub. The fix is to borrow the installer/removal tool from autozone and back off the air gap a tad. This can be done on car, without removing compressor or refrigerant, and can even be done without removing the shaft nut since the nut does not bottom on the clutch drive. Pull back the plastic cover in wheel well to access...

Thanks brcidd

Seems that giving that clutch plate a bath in WD-40 completely quiets it down when the AC is off.
I livev in Minnesota. I hope this compressor/clutch will not affect my heat in any way

Excellent call by brcidd. It is fairly common for these clutches to make noise when disengaged due to improper gap and/or damaged spring plates. The other possible problem is the idler bearing for the clutch sheave, but the clutch plate clearance issue is far more common.

I was a product engineer on the V-5 back in the 90's- the reason the gap gets closer is because the entire clutch assembly was e-coated (as an assembly) and the area behind the rivet heads (the stops) are not coated- so corrosion builds up there after 10 yrs and the stops are now longer with the rust underneath, and the gap gets closer faster than the armature plates/pulley faces wear.

Very, very common issue.