I think you answered your own question.
In the vans you'll have to replace the compressor, because unlike the intrepids, van's use one serp belt to power everything.
not sure if thats true with all models.
The 3.0L didnt run with one belt. It had a separate belt just like the 3.5L intrepid.
If the ac is screaming, the solution is pretty simple.
A few tests that you can make.
1. while in park turn on the ac, make sure its hot enough that you can tell when the ac runs.
2. If the ac blows cold but screams when turned on, thats a good sign.
3. If the ac just screams and doesnt blow cold then read below.
Ok so if 2 is true, then all you need is a new ac clutch, basically the compressor isnt engaging properly. My dads voyager had the same issue a while back when he had it in like 2001 (he had a 97 but im sure they are the same as the 98).
All you need to do is get a new clutch and just swap the part with the pulley on the compressor, its pretty simple, just remove the pass side wheel and you are all set. You dont need to discharge any lines or remove the actual clutch assembly from the compressor.
Just pm me if u run into any issues, funny i actually recall the procedure even tho i was only about 15 at the time. I do remember the clutch was about 110$ complete and only parts of it were used, you may have to solder new wires on the clutch, you will see a plug that comes to the clutch.
Be sure to take some pics for us.