I called the incommand people (ASA) about this. From the tech I spoke with, it should be connected to the fantastic fan, but on our Montana, and by the sounds of it yours as well, it is not. So, it pretty much does nothing if it does not control your fantastic fan, its not gonna do anything.
I was thinking it was like your car where it would either choose to suck air in from the outside or re-circulate it from the inside, but it doesn't work that way. I didnt think it would as the A/Cs we have, have been the same design for the past 15 or so years.
For sake of mind, i just put it on closed.