Use the defroster with either hot or cold air but make sure the A/C is on. It usually clears up foggy windows rapidly. If the A/C isn't on the windows will usually fog up even more or just take forever to defog.
Sounds like opening or cracking the window is one option
heres another I saw on autogeek http://www.autogeek.net/auto-glass-defogger.html
I figure I test this out and give it a review if its good or just a waste of money