Belt slipping

[dbut10]

Hi

I have a problem with the serpentine belt squealing on my 97 Mystique. The belt runs fine on idle, even with the A/C running, but when the gears are engaged the belt makes a squealing noise. It doesn't though when the A/c is off. Sometimes it will squeal though when turning the steering wheel while stationary. I am guessing that the extra drain of the A/C (or power steering) is causing the revs to drop and the belt is slipping.

I have changed out the belt and inspected the pulleys. The compressor doesn't seem to be a problem either - it doesn't make a noise when the car is parked and idling and cools just fine. The belt tensioner looks fine but does anyone know whether these are susceptible to the springs giving out? Should I take a chance and just replace the belt tensioner in the hope that it will cure the problem?

Any help gratefully received.