Winnebago had some problems in the '03 timeframe with the ac duct separating behind the rear cap. Owners could feel the right side of the rear cap on a hot day and find it cool due to the escaping air behind the cap. For some, the separation was where it could not be reached without removing the rear cap. Sounds like ours is where you can reach it.
Either way, I recommend you talk to Winnebago Owner Relations at 800-537-1885 or email to [email protected]
. Be prepared to give them your coach s/n. I would imagine on an '06, they would be very likely to take some responsibility for the repair.
Now, if I can just get their $ assistance with my water leak problem ...