On not knowing how much freon you put in, get yourself a small kitchen scale that measures ounces. My wife has one that I use, just slip it into a gallon ziploc and I don't have to worry about contaminating our food with garage. Weigh the can before and after and you will know how much you have even with partial cans. If using one of those can trigger jobs with the foot long hose, make sure to weigh every time with it either attached or not attached. I'd do attached just so you don't have to wonder how much of the last can went in.