After the car is back together I plan on converting to 134A. I was planning on changing the compressor, drier, and expansion valve. Is it necessary to replace these componants if they have not failed? I also remember that I was having problems with my climate control. It seemed to blow hot air whenever it wanted to causing the A/C to not work very well, or no heat when it was freezing. Occasionaly it would work good. Not very sure where to begin looking. I do plan on changing all the vaccum lines in the engine compartment when the engine goes back in.