Wow, small world, ain't it? I was just pondering the same dilemma. Not about fogging up, but about proper operation of the climate control! The deal is this, you shouldn't EVER have the system shut off except " in case of bad odor or automatic car wash"
. And I'd like to think that we are all too sophisticated to use an automatic car wash!
The rest of the time, it should always be on! To completely defrost the windscreen, you need to press the button with a picture of the windscreen on it. To defog the windscreen, you press the button with two white arrows on it, as JCE already pointed out. But then, you should go back to the either the "normal", or "economy" setting as soon as possible. If you still have an owners manual, read up on this stuff!
One other thing, when my Aerostar had a problem clearing the windscreen, and the problem actually worsened
using the defroster, I found that the culprit was the heater core, which had just died!
[Edited by longston on 02-03-2001 at 09:14 PM]