Yep, the new compressor is junk now too. The old compressor died a black death, and shot metal shrapnel through the system. The proper repair is to remove the condensor and evaporater(s) and thoroughly flush them out with both a flush solvent AND air, then flush out the lines the same way, before ever putting a new compressor on, adding oil, pulling a vacuum, and then adding refrigerant, all in correctly measured amounts. Did you pull a vacuum before putting in the refrigerant? If not, you had a lot of air in the system, which likely accounts for your high low side pressure. You did replace the drier, didn't you? That's pretty much a given whenever you open up the system in the manner necessary for a compressor replacement.
This is NOT the "overkill" method. The is the method that will let your A/C work for at least a couple of years, hopefully longer if done well. Yes, getting to the front evaporator in a Caravan/Voyager/T&C is an absolute nightmare from what I've heard - have to remove the entire front dash to get at it.
See
Auto AC Forum for more info.
Chad