'98 Grand Caravan A/C

I have an a/c compressor that was replaced about 1-1/2 years ago in a 98 Grand Caravan. A/C was working fine blowing really cold until one day about 2 months ago when it just cut out about an hour into a 3 hour highway roadtrip and has not worked since. The compressor no longer engages at all. I had put a low side pressure guage on the system about 2 weeks before it went out (just to make sure it had enough charge) and the reading was perfect. Immediately after it stopped working I read the pressure again and it was extremely high. I also have tested both a/c fuses (20a & 40a) and they are both fine. Any thoughts? How might I test this further?

Thanks,
Dave