Braddlee (and SneakyBaron) may be on to something here. Played with the recirc function yesterday and as soon as I turned it on my windows began to fog up. So, naturally, I turned it off and flipped on defrost.
I haven't been able to test timing because every time I have tried to use the recirc function, it hasn't been good for my visibility.
Curious to try it in the summer time (or at least when the temps warm up) to see what happens.