Thanks for the info 4LO 4.0. I have heard of phosgene gas from a/c and refrigeration class I took at a tech school years ago. when you solder the refrigerant lines and there is freon present, it will make phosgene gas. And as our instructor always said, " Phosgene gas, just so you know, that sh** will kill you!" Definately pay attention to what you clean your weld area with. Randy