I recently purchased a 3450TS Big Country and do not know how to close the Hood exhaust vent outside door. Is the opening and closing automatic? On my former Cougar, I had to manually close the vent on the outside before traveling because it would flap in the wind. So - is the vent automatic or must I find a button to push or a lever to close? I cannot find anything in the manuals and the service dept could not answer the question. Help!