This will severly limit the amount of fresh air that gets into the cabin, so the air will tend to be stale and filled with moisture (from your breathing and sweating). This will lead to window fogging.

I haven't notice this hot air problem, but I usually keep the A/C on auto (and not recirc) unless there is a specific need to change.

 

I have this same problem.

 

Which problem, breathing or sweating?

 

haha..both

In the summer I can feel heat coming through the vents and no matter what I do it doesnt stop.