JaxDad wrote:
ArchHoagland wrote:
Always close the roof vents and windows when you are running the air conditioning whether it be parked or moving down the highway.
The air conditioners bring their air in from the interior of the coach. If you leave the vents open then you are drawing in hot air.
Actually that's wrong.
Unless the dash a/c is set to 'max' or 'recirculate' the system cools outside air and vents stale air. All vehicles operate this way.
As for cooling efficiency, if you leave the rearmost roof vent open (hot air rises) and set the dash a/c to highest fan and set to blow down the back the hotest air will be drawn out the roof and the cooled air will be drawn towards the back to cool the rest of the coach.
I've been doing this for years and have proven how well it works to many non-believers over the years.
On a typical dash unit the blower fan is the weak part and it usually can't keep up with the cooling capacity of the rest of the system. This method dramatically increases air flow and really helps.
I believe (but I could be wrong) this thread is referring to roof AC's with vents open/closed. Otherwise I agree with you, if I can be comfortable with only dash AC I'll also leave a rear vent open to allow warmer air out. I also have vent covers otherwise I think traveling with an open unprotected vent is not a great idea.
