If you have a vent that is capable of being a 2nd AC position, and you don't have the 2nd AC, I think there is wires there. If you want to put one in the BR in place of that nasty little fan in there, you should be able to install one there also. As far as the other crank up vents, I don't know if there is any wires placed in there when they built it or not. You might place a call to the manufacture and see if they know.
__________________
|