1999 9200 Air Conditioning has me stumped

I think you've got a gauge/hose issue.

How is your compressor turning with no freon? And it's not freezing up at 70 psi, and it's not gonna freeze up with a bad compressor.

Check those hoses and the manifold for a messed up schrader valve, or O ring that is pinching flow when you tighten the hose

 

I'm talkng about the hoses on your manifold set

 

You mentioned the compressor being mounted on an angle. Is it the exact same as the old one. They can only be angled so much. I’ve had to clock the head on mine once, only because I changed the head/hose fittings. Basically hoses need to be connected on upper half. If I remember correctly, compressor can’t be mounted more than 90 degrees either way. It may be just for oil fill plug acess. Assuming it’s a Sanden compressor. If you have a York, my sympathies.

 

Only thing you did wrong according to your description- You opened the gauge low side first, then the tank. Should open tank first, bleed air in line from shrader on guage, then open gauge to fill w/o any air. I doubt that the cause of your problem. Have to ask. Did you run a vacuum for at least 45 minutes? Let set for 30 minutes, checking for leaks? If so. No answer needed. Just wondered.