Since the weather around here has been getting quite a bit more chilly I have been using my heat more often. I believe this has been inducing some horrible headaches. When I have the air on recirc I'm fine, but when I change it to the fresh air I get a faint smell of exhaust and after 5 minutes I have a headache. Is this common? Am I just a hypocondirach (SP?)? Is there a way to diagnose it? If it could be an exhaust leak..... Is there a way to fix it? Thanks!