I've had some help troubleshooting the unit, here's what we've come up with so far:

The climate control seems to be working. Defrost works, and it will put out heat if you move the temperature wheel (as it should).

There is an audible click when a/c is engaged, and the engine sounds like it is under a load. You can turn a/c off and it'll disengage, turn it back on and you hear the click again and the engine is again under a load (so everything there seems to be working fine).

I got lost when the monovalve was mentioned, I need to do some research and find just what that is so I can clean it off and make sure it's not sticking. Also I hooked up the gauge to check pressure on the low side, it shows about 55psi when the a/c is turned OFF, and doesn't register anything when it is turned on.

A very, very stupid question...how much refridgerant should I be using? I stumbled on a page that said it would require 100g??!! If so, then I haven't even put half that in. Plus, I read somewhere else that R134a only needs to be charged to 75% of what you needed with R12.

Maybe I should just get some more R134a and see what happens. If I already screwed everything up, can't hurt right? I'd sure hate to waste $7 a can if that's not my problem. Might be something to try in between reading up on a/c systems.