An observation regarding the fresh air door. On my rig, the fresh air door is spring loaded to the open position, requiring vacuum to pull it closed.
So if I try the method of switching to Max AC, then removing the vacuum line, it instantly returns to the open position, before you can say, "what the ...."
Are you folks sure that you are not needing to tie the door closed with wire or something?
6/18 2011 Tiffin Red 36QSA, 340hp ISB, Our 3rd Class A, Me GL1800 & DW GL1800 Trike, 757 ret., 510 club