1994 was the year of all r134a conversions. I think you can walk in your auto parts strore and buy a can of 134a..you can here in Los Angeles. r-12 freon is gone, you may have to jump the Mexican border to get r-12.
All you need is a 1 1/2 lbs. or 22 oz. worth of 134a and a an adaptor to fit into the system.