Did they really open it up to check it, or did they just observe it from outside the dash?

It is not altogether implausible to think that a connector that isn't snapped in all the way can be working properly for the pins that are still making contact, yet not for the pins that don't make good contact. Likewise, the loss of a ground contact could have an effect on some systems differently than others. Signaling AC activation is a far different (simpler) operation than varying fan speeds in my estimation.

 

They took it all apart and reconnected everything going to the a/c console but what you say makes sense so the only thing I could do is reconnect everything back into the harness hoping that when they reconnected it one of them still isn't connected properly and if that doesn't work still I'm gonna have to go to the dealership and probably pay just for them to look at it lol

 

I guess I don't understand why you are left to figure this out.

Just becasue they couldn't conveniently figure it out in short order doesn't mean they satisfied their obligation to make it right.

Look, if you took your car to a "professional" shop and had them install something, after which something else in the car which is in very close proximity is no longer working, something they very likely had direct contact with, and something that is certainly rare and atypical to fail in these cars, then common sense says return it to them and demand they figure it out. I'd be screaming at them and calling the Better Business Bureau to report them.