You could run a jumper for testing, but I wouldn't use it like that. You are bypassing the system and the compressor will not cycle which will lead to other damage.
As far as the issue. Do you hear the compressor cycling when the engine is running? Also, has the air temperature actuator been checked or replaced? I know that sounds elementary, but you didn't mention it.
Also, you have me lost on opening the window. In my mind, there is no correlation between the two. The only thing I can think of is if the blower motor is not working and opening the window creates a vacuum drawing the AC through the system into the cab.
When you turn the AC on, I need to know if the compressor is engaging and if the blower motor in the vehicle works. Additionally, are you able to change from outside air temperature to the heater?
You mentioned Freon, pressure switches, and so on are all good, so I'm not focused on that.
Hang in there. One way or another we will get this fixed. We have one of the best HVAC people here. He owns the site, so we will call on him if I can't figure it out.
Wednesday, June 22nd, 2022 AT 5:21 PM