Always open unless we are camping and it's particularly hot and humid. I discovered we get quite a bit of condensation in the bathroom (that's where the vent is) along the AC ducting pathway in the ceiling and lots of warm air pouring in through the vent. Always open in the storage lot.
2013 F-350 CC SB 2WD 6.7PS
2013 Eagle Premier 351 RLTS
-SOLD- 2012 X23B
-SOLD- 2003 Ford Expedition 5.4, Bilstein shocks