Scrapping air conditioner units and furnaces

Depending on how they was disconnected the tech can easily close the liquid line(smaller line) and run the compressor for a short time. Doing this while watching the gages,if the line is short enough,the refrigerant can be pumped back into the outdoor unit. Again while reading the gages the suction line will then be closed and the refrigerant will be captured in the unit. If the valves are on the unit then the only way to tell if unit has juice is to crack a valve quickly and make a determination .