Very bad for the environment? I know that's the reason why they made us all switch, but come on..... how's that global warming thing going?!?! (Just making a point about about our awesome EPA and the science/politicians) I know the fines are huge IF we get caught, and that's only if we break the law and vent the stuff, but I have never heard anyone (until now) argue that r13a is as good as r12. I have seen the numbers myself (the boiling point of r12 is a little lower than r1234a) and am not rying to get into a tech war. Especially when so many people on here know so much more than me. My question is about adding r12 to a r134a system. I know you need to be licensed to buy it. I furthermore know the license is extremely easy to get and once you have it, it's yours for life. What I do not know is if the two are comapatible. I know you can buy those little retrofit kits for about $10 and dump 134 into an r12 system and it works fine. How about going the otehr way?