Hello Bcracing and
. We are glad to have you join us here and we look forward to reading of your adventures and experiences. I am sure you will enjoy the website and forums. Good luck and keep us posted.
The floors of the slideouts do not seal out the air by sitting flush on the floor. This is accomplished by a seal at the outside edge of the floor and sometimes even another seal on the bottom of the slideout flange. With the room extended, inspect this area where the slideout floor and the main floor meet. There should be good seal here. Also look at the bottom of the slideout flange. If it looks like a seal was there at one time, this could be the problem as well.
Let us know what you find.