The crap you're buying in small cans is just that, crap. It usually contains a sealant that reacts with oxygen to form a plug (to "fix" the leak that caused the loss of refrigerant in the first place), and when you fail to evacuate your system before shooting that garbage in, it will eventually just gum up your entire system. The chemical compound itself usually contains hydrocarbons like propane and butane, which have similar properties to the refrigerants that are supposed to be used, but are flammable hydrocarbons...!!! I hate dealing with a system that has been contaminated by crap like Duracool or whatever, I refuse to hook up my equipment to something that has the mechanical equivalent of an STD.
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