I have been reading about 134a retrofit, etc, etc. seems kind of like a pain in the ***. since they eventually want to phase it out as well, in my situation what woudl be the best solution. I mean I will save money if I repalce the compressor myself. Can you just charge a system with freeze 12? or is that only added to existing r-12? the system currently works fine there is just a horrible vibration once the clutch kicks in.