I have a 99 Town and Country, 110k mi, 3.8 that I have an a/c problem on. My wife called me and said the van had overheated a couple of blocks away and that the a/c quit working. I let it cool off and drove it home. When I checked it at home I noticed the compressor was cycling on and off. Tried to add can of R134 but the system would not suck it in. Put the gauges on it and both low and high sides had extreme high pressure. The compressor is cycling because of high pressure not low R134. I'm thinking one of three causes: expansion valve, compressor, or moisture in the system. Please help.