2010 GMC Terrain Recirculation vent issue

[Champz65]

The recirculation vent on my 2010 GMC Terrain opens on its own after the car is shut off letting in extreme humidity in the car. What position is the recirculation vent supposed to be when the car is off? I live in Florida where the humidity is 100% most of the year. The car feels damp when you open it and I have had damp rid hanging to avoid mold. If the vent is supposed to be open when the Car is off what is all of sudden causing all the humidity? It started this a few weeks ago.

[Doug_Scott]

Have you noticed you have to select the recirculation button every time you start the engine?  I don't have auto HVAC in my truck, and it resets itself sometime between the time I turn the engine off all the way to the time I restart the truck.  At that point I have to reselect the recirculation button again.  You may want to check the floors for any water being held by the carpet.  I had a 98 Pontiac GTP that when it rained the drivers side floor would be so wet that the WeatherTech floor mat would be floating in the water.  No matter how dry I got it, it would be humid in the summer, and would collect frost on the inside of all the windows overnight due water on the floor.  Leak ended up being from the seam of joint between the door plug and the roof(the seam you can see on the roof at both sides, a couple of inches in on each side of the roof.  Dealer didn't have any idea of how to repair it, I didn't really care, told them to just seal the seam up with RTV or some 2 part epoxy.  Car was leased.