There wasn't an auto a/c forum so this seemed the best choice.
I read an article the other week that really got my blood boiling. If I locate it again I'll post it, but the summary was that most of Europe is looking to phase out R-134a, not because it harms the ozone (which it doesn't) but now because they claim it still carries "global warming potential". In other words, I read this as the patent is about to expire, they need some new wonder refrigerant that is even more environmentally friendly so the manufacturers, DuPont I guess, can make some more money. This is the same stuff we went through with R-12. If Europe embraces this, it won't be long before the U.S. has to be politically correct too and we're in the same boat.
So my question is why can't, say, ammonia or carbon dioxide be used for auto a/c cooling? I admit I don't really know much about the two refrigerants except that ammonia attacks copper and I think carbon dioxide has to operate at much higher pressure than most commercial refrigerants.
I understand why some people don't want to switch over to either of those two...it's all about the money....but are there practical/technical reasons why either of those two could not work for auto a/c?