What do I need to do to make my 94 r12 compressor play nice with my 96 r134a system?

 

you need a retrofit kit. then evac the R12 & charge with R134a. people will tell you that the oil has to be changed also, I've never had an issue.

 

also I've found for the older XJ's if the system is empty it takes 2lbs, your head pressures should be around 45psi on the low side and about 250psi on the high. the newer XJ's seem to only need 1.5lbs to get those pressures.

 

What do I have to do to the compressor. The ac system is all ready for 134a it's just the compressor. Does it need any thing or us it ready to go as a swap

 

nope, charge and go.