Sorry to say you will have to replace it. You can not free it up, and if you get it freed up it won't be free for long. The bearings are worn out and this can be cause by two things normal wear and tighten it to tight>
You can do that by replacing the tensioner
Here it is:
by taking it to a mechanic
no!
There should be a diagram under the hood for that year.
Go to www.autozone.com and look under specifications, belt routing. On a 1989 Dodge Grand Caravan, the diagram is on the side of the engine where the S-belt is located.
Not sure ,but it costs $115 to change mine on my 1998 Dodge Durango.
It is the item in the serpentine belt that is the lowest and furthest forward.
The belt tensioner is self-adjusting.
Fit a new belt tensioner
Rear most and lowest pulley on the serpentine belt.
SHOULD BE ON THE FRONT MOLDING UNDER THE HOOD....WHERE IT SAYS WHAT SIZE ENGINE YOU HAVE