What do you use to put freon in a car?

if you have a small can of refrigerant you attach the specially made hose to it. then connect the other end to the vehicles low pressure fitting. this fitting is always on the larger of the 2 a/c pipes. start the engine, turn on the a/c and if the compressor works properly the can should be empty in a few seconds. remove the hose from the vehicle first while the engine is still running with the a/c on.