AHA! That explains that extra vac port on the intake right near the coil that had the plugged off hose running to it. Now assuming that whole setup in the cab doesn't leak vac all over the place, I should be good to go. Even if I do find leaky parts I'll know which direction to go in troubleshooting. Thank you very much for the info.

The A/C I had figured there was something to keep it from eating the compressor if lost its charge. I may just have to bite the bullet and take it in to a shop for A/C diagnosis. I have access to a lot of the equipment, but I can't discharge the system and recapture. I'd be wasting dollars trying to leak test it by just charging it over and over.