2.375 pounds of R-12 is used in the 91 Reatta.
If your system is empty, be sure you evacuate the system with a vascuum pump for about 30 minutes. Then be sure it hold the vacuum. If it does not hold a vacuum, you have a leak and all your precious R-12 with disappear..
Just a hunch, have you checked that the antenna cable is plugged in to the radio module? I think I had this same problem on my 89, but it was a long time ago.