We have a 2014 Crossroads Elavation toy hauler. While on the roof I noticed a cover missing from a small round thing. Location: center of the roof, right over the storage area above the sliding glass doors. This round thing is about 5 inches in diameter. On the inside in the storage compartment where this thing is, where is nothing in that area. Again, the cover on top of this thing blew off and I can't tell what it does if anything. Can anyone help?