From the bloggers at Everything About RVing.
My motorhome has ducted AC vents in the ceiling. The cold air goes down of course. My question is, “should I leave the roof vents open to exhaust the hot air?”
No, you should keep all windows and vents closed when operating your RV’s Air Conditioner. Now if your RV is super hot on the inside and it is cooler outside, you may want to open up some windows, vents, doors, etc. before turning on the AC unit. Once the excess heat is out of the RV you can close everything up and turn on the Air Conditioner.
Now if your RV was equipped with a Swamp Cooler instead of an air conditioner, then the answer to your question would be yes, because swamp coolers cool more efficiently when some windows and doors are open and the humidity level is low.
To read the full story by Everything About RVing, click here.