Sometime ago I began to experience belt screech in a '95 Rodeo 3.2l 6VD1 motor. Occurred when I activated the A/C. Sometimes it was brief in duration - other times it would last longer - more often when warm and primarily when idling. Belt tightening offered minimal and short-lived help as did completely changing out all 3 belts: Alt/A/C-Pwr Steer. A set of dealer Bando's were replaced with A/C Delco belts.

As time went on - I began to notice that if I activated the power windows with the A/C on - the screech would last for as long as I held the window button(s) down. This situation would come and go. I discussed with a local elect. rebuilder - he said the alternator had gone "full field" - couldn't handle the load. Coincidentally - I would notice a drop in voltage from the factory dash mounted volt meter.

I had planned to remove the original Hitachi alternator for rebuild. This would be it's second in 16 yrs - 260,000 miles.

A few days before I was going to pull the alternator - my harmonic balancer fell apart. First experience with this problem. The unit was now in 2 pieces - one being the heavier part up front that contains the power steering pulley and shaft that connects to the crankshaft; the other being the rear section that contains the alt-a/c pullies. The 2 rear pullies were rattling around(as one) and both alt/a/c belts had been thrown.

Sourced a 3rd party harmonic balancer - Dorman - wear item - not a junkyard part for this man and took alt in for rebuild - brushes worn - armature turned.

At first I thought the screech was related to the weak alternator - but I'm now more inclined to believe that my slow-dying harmonic balancer was the real culprit all along.

On my Rodeo - when the a/c is activated - the viscous fan is also engaged and that creates some drag on the harmonic balancer.

I performed countless visuals under the hood when the screeching first started and more look-see as it continued - yet never saw anything that looked like a harmonic balancer coming unglued. I may have simply missed the signs of a dying harmonic balancer.

I replaced the now damaged A/C Delco belts with Goodyear Gatorbacks. My research led me to believe they were of sound quality. Ironically - a couple of days after bolting everything back together - I found a post on another Isuzu forum that JLEMOND(Jerry Lemond) had replied to. He made it quite clear what he thought of Goodyear belts - said they "stretch like rubber bands".

Learn somthing everyday.

Maybe this will help someone else.

Just my 2 cents.