2006 Winnebago Outlook / E450 Cab AC issue

So to be clear, are you thinking that the previous work done, which resolved the AC going through the defrost vents under load, is now just not closing the vent to the outside air during max AC? I would love to have supporting evidence that their prior worked failed and they should fix it as a warranty item (albeit a year is probably longer than the warranty, just not sure). I am not very mechanically inclined but love the pics from your fix on the other site.