I have a 1987 Ford Van, E250, 6 cyl, AC. Squeals when started and chirps when AC on.

Michael, November 2005

Ok usually if its a serp belt sometimes it just as simple as replacing the belt ....check belt tensioner and alignment of pulleys ....the reason the sounds changes when you put a/c on is theres more tension put on the belt whens its on ...I have seen people put belt dressing on them and it works ...I have also seen my brother in law take a soap bar and rub it on belt while engine running and it fixes it for a while

bg, December 2005

Check fluid level as this contains lubricant..check belt tension...check coupling action ..should switch on & off...This can get expensive if you run it while defective ..another trap, ....designed to fail ...and you pay again.....

lobofuego, December 2005

bg,
Thank you for your answer. Note that this vehicle has only a serpentine belt.

Michael, November 2005

Sounds like you have a loose ac belt or just worn out
Check belt and make sure there are no cracks on the inside of V belt ....proably have to take off other belts to replace it so check them also ...no need for doble trouble ...if ac belt is worn the others proably need to be replaced anyhow

bg, November 2005