my windows foged up the other night when doing corn, i thought it was odd, but then again i had a sweet young gal in the cab with me!! i blamed it on her *smiles*. get some "rain-x" anti-fog and wipe it on the inside windows, it really works good!
get some "rain-x" anti fog wipes, and wipe down the inside of your cab windows, they won't fag up anymore, that stuff works great! also if you use the "rain-x" on the outside windows, the dust won't stick near as bad.