Volvo Repair: 240 DL -Is it R12 or R134a?, expansion valve, freon

Question
How can I determine what refrigerant I have in my 1989 240 DL Sedan? The fitting on the back of the compressor is the same as the 134a quick connect (at least I was able to charge it that way), but system won't hold a charge anymore, and I am afraid I added 134a to an R12 system and created a problem. The system leak appears to be around the compressor as it is very oily in that area. Have I plugged the drier perhaps? Can the compressor seals be replaced by me or must I get a rebuilt one?

What is yourm recomended sequence to solve this problem?

Answer
IF IT HAS A 134A STYLE FITTING IT HAS PROBLBY BEEN CONVERTED.BEST WOULD BE TO REPLACE THE COMPRESSOR RATHER THAN REPAIR IT.I DOUBT THE DRIER GOT PLUGGED UP.TO BE SURE OF THE LEAK YOU MAY WANT TO HAVE FREON AND A TRACER DYE ADDED.THIS WILL SHOW A LEAK WITH THE USE OF A SPECIAL LIGHT.IF IT IS THE COMPRESSOR i WOULD REPLACE THE COMPRESSOR,DRIER AND EXPANSION VALVE.