I was getting things together to get started, new drier, new expansion valve, refrigerant and 'oil..' I was going to draw it down today-- and get to work this afternoon.. My freeze-12 (drop in "Freon" replacement) arrived a couple days ago.. Here's my problem.. Uncapped the lines, to find one has been "retrofitted" to 134a. My questions are: 1) can I just wrench that off?? It looks like it's just a screw on fitting. 2) the BG refrigerant oil is compatible with both 134 AND R-12 "freon" so I'm thinking that isn't an issue.. 3) do I need to replace the receiver drier and expansion valve, and pretty much, go on with my life?? BTW-- my compressor clutch connected and ran for a few seconds without horrific noises.. I think I'm okay there... I'd really PREFER to go back to the R12 (Freeze 12) setup. One, it's already paid for, two-- it's closer to what 'Ma Benz designed the system for.. 134 seems fine, for what it's designed for-- I've never been impressed with it for retrofits... I did a couple for others when Freon first became scarce, and before reasonable alternatives like Freeze-12 were available. Their systems didn't work 'as well' or blow 'as cold...' The compressors seemed to die about 2-3 years later.. We told ourselves they were old compressors-- but I now understand that 134 operates at higher pressures-- and that stresses the compressor more.. Anyway-- any help would be appreciated.. AJ