And yes I did try to find this via search. My 83 300D was retrofitted with 134A and I need to add some to the system. My hopefully simple question is do I charge as a liguid or as a gas, can upside up or upside down. I will be charging with the compressor running as I did put enough in to get the low pressure switch to engage. The system was not completely empty and I am not doing an evacuation and it is blowing cold with the one can of refrigerant + oil that I did put in. Advise greatly appreciated. Thanks Much.