Date: Mon, 27 Jan 2003 12:24:15 -0500
From: tom reingold <>
Subject: Re: Saab 9000 fogging up

Fannie Schapiro M.D. & Daniel Krill wrote: > My wife's 97 Aero is fogging up within 20 minutes of driving on these cold > Rochester mornings lately. The mechanics she uses (Schoen Place) have > replaced the heater core twice already, specifying that as the problem. Why > would the heater core cause the interior to fog up (and ice over, lately) on > the inside of all the windows? It seems to me that this is more of an issue > of recirculated air and not getting fresh, dry air from the outside to dry > out the interior. > > Also, for some reason, the manual says to increase the temperature to 70 if > the interior fogs up. Why would this work? It seems counterintuitive, since > on normal cars to defog you turn on the air conditioning. Since there is no > independent AC control in the 9000, the only thing to do is to change from > recirculate to fresh air, or turn the temperature DOWN to get the AC going. > > What's going on here? > > Thanks for any information. > > Dan She should always have it set to fresh air. If she has it on recirculate, then that's the reason for the fogging up! The moisture from her body is building up on the windows. A/C works to defog because it dries the air. Sometimes, in extremely humid, cool weather, I turn the A/C on to defog the windshield. I don't know about the 9-5, but the 9000's automatic climate control has a setting for "LO" which means maximum cooling. She could try that, but she won't want to run it for too long. Another thing to try is some repellant on the inside of the windshield. A chemist friend of mine taught me the trick of rubbing the window with bath soap. Then rub it off with a rag. He said it leaves a "mono-molecular layer" of soap which has an effect but is clear enough to see through. Some people find that newsprint does the same job. Sometimes, fogging is from outgassing of plastic from the dashboard. There, the newspaper or soap trick might help. -- Tom Reingold Noo Joizy

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