Re-charging refrigerant AC without starting compressor or engine

Call To a body Shop to perform air-conditioning Recharge after an accident and a Refrigerant line was replaced that was just dented severely.
Sometimes I get to the shops and somebody forgets to put coolant in the engine or inverter on a hybrid or electric vehicle. Or often the shop ran out of the correct coolant when I get there and I just have to perform and air-conditioning service without starting the engine or the Electric compressor’s it works fine every time something I have perfected over the decades.
I did not invent this procedure it has been around forever it’s something my dad taught me when I was 12.