Now that I purchased my new A/C compressor I need to know what some of you think I should use for a refrigerant? The shop that I use is vary good and the mechanic is a friend of mine and knows GN's and my car vary well. The problem is that they are bound by law and have to use 134r if I choose to have them provide the refrigerant. However my mechanic said he would use whatever as long as I provide it. I would rather use R12 but it's hard to come by in my area and quite expensive. I hear that HC12 is vary good and environmentally friendly but combustible? I have also heard that 134R won't blow as cold as R12 in older systems and can be corrosive to them?