[silicon212]

First off, thank you for your service to our country (US).

Secondly, have you put an actual manifold gauge on both the low and high side, or just one of those hoses with a gauge on the low side?

If you have run a manifold gauge on both ports, what is the high side reading?

Another thing to check for is crud built up around the evaporator coil, crud on the condensor, etc. Is the compressor cycling - i.e. are you getting your low side reading about 30 seconds after the compressor kicks on? Sometimes, I've noticed with my R134a conversion on my '88 Caprice, that a static reading on the low side can be well over 70 pounds, but once it kicks in and stays running for a bit, it tends to drop down to around 30 PSI. If it's low, the compressor will cycle even if one of those cheap gauges on the low side reads in the red - that's why the manifold gauge is needed, to see what's happening on the high side. The high side pressure should roughly be 2.5 times the outside temperature (i.e. 100 degrees outside you should have 250 PSI etc).