I had the exact same problem on my '93. The problem was the screen in the orifice was clogged. I knew nothing about these but it wasn't that hard to change. When you buy a new one you'll need a special tool that releases the connections. With this thing clogged all the 'freon' in the world won't help.
I think my problem occurred right after I switched over to R-134a. Don't get it over pressurized. I did on mine and blew out a seal on the compressor! Below is a photo with a black ring around orifice:
