[bob deluke]

Bill;

You should have a set of refrigerant gauges hooked up to the suction/discharge ports. Without knowing pressure in system, you are just guessing at conditions. If your tank temp/pressure is lower than system pressure, the gas from the system will go into your R-12 tank. You need to have a higher pressure in your R-12 tank than the system pressure. Without gauges, you are taking a w.a.g. Nothing like overcharging a system and having it seize the compressor! If you are unsure of how to charge a system, take it to someone who knows what they are doing. R-12 is very expensive and almost non existent today. You cannot buy virgin R-12 anymore, most is reclaimed and if not done by a reputable company its garbage.