Does air conditioning work with window open?

The AC system itself will continue to work... it won't be as efficient, since one of the functions of the AC system is to remove humidity from the passenger compartment, and an open window is constantly reintroducing it back into the passenger compartment. It won't effectively cool with the Windows open, since warmer air is going to be constantly going into the vehicle via the Windows. But the AC system will still function the way it normally does.