Okay, I hate to post about a heater problem when there are already two other heater problems on the forum, but it is wintertime so I guess heater problems are pretty common right now. I think I've got one for you that you might not have ever heard of before. When I go out in the mornings to crank my car, I turn the heater and windshield defroster on. Half an hour later, I come back out to get in the car and go to work, but the heater is still pushing out cold air like it no longer works. As soon as I put the car in drive and start down the road though, the heat kicks in. As soon as I stop the car (say at a stop sign or red light) the heat disappears. Start driving again, get heat again. Stop driving, lose heat. Repeat, repeat, repeat. What gives?!