[Supras] Air conditioner problem

[JAMES]

Hey,
         Thanks for all the replies. I checked the online TSRM and you can remove the evaporator with out removing
       the dash. I think I will check it out my self to see what condition its in.
       What does the expansion valve do? And how can I tell if it is bad?
         Since I am going to do it my self, I am going to convert it to R134A.
         I read on a can that said it was compatible with oils that is used with R12.
       If this is the case, can I just charge it up with out doing any thing else?
       How many of the 12oz. cans will I need?  
        Thanks for any info and I will let you know how it turns out.
                                                 James