How do they charge the ac at the factory?

[GMBoy]

I would bet the whole process is automated and the only thing anyone does is hook hoses to the vehicle.

That is exactly right. One operator hooks the AC connections and coolant fill hoses in the engine compartment and hits a button - all automated ac charge and coolant fill. Takes approx 50 seconds. The operator also fills approx 6 gallons of gas into the thank as well.

 

[GMBoy]

Yes but I am thinking the HVAC supplier charges the system prior to sending it off. Hopefully someone with knowledge of the assembly can chime in here.

Nope. The ac components are all installed at different points in the assembly line and cannot be charged until the system is complete and sealed.