defroster wouldn't shut off
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Joined: May 2009
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From: Dracut ma
defroster wouldn't shut off
After being parked for four days in a rain/mud soaked field, I was at a horse show, the defroster would not shut off even when I hit the off button. I could select anything, AC Heat, floor or dash vents and no problem. All worked fine. When I would shut the climate control off the defroster went on and at high speed. After an hour drive home, the problem was gone. No leaks under dash ( had a GEM go crazy on my Expy from a windshield leak) Any idea why it would do this?
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Joined: Sep 2000
Posts: 23,174
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From: Stephensville WI
You have a vacuum leak.
The heater system runs on vacuum, either manifold vacuum (gas engines) or from a vacuum pump (diesel engines). When there is not enough vacuum to run the system, the default is blow hard through the defrosters. It is a safety feature.
A likely cause of the leak is related to the 4 wheel drive Electronic Shift On the Fly system (ESOF). A safe bet if you have ESOF is your front hubs are not locking automatically either.
The heater system runs on vacuum, either manifold vacuum (gas engines) or from a vacuum pump (diesel engines). When there is not enough vacuum to run the system, the default is blow hard through the defrosters. It is a safety feature.
A likely cause of the leak is related to the 4 wheel drive Electronic Shift On the Fly system (ESOF). A safe bet if you have ESOF is your front hubs are not locking automatically either.
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Senior User
Joined: May 2009
Posts: 150
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From: Dracut ma
The auto hubs are working. I can also switch to floor vent or the defroster or dash. I just got back from another trip and everything is fine. I looked into what ETAC is and it's problems. I'm hoping it was a one time thing.
I did find this. If it happens again, would this provide a clue?
http://www.aircondition.com/dsmobileac/eatc.html
I did find this. If it happens again, would this provide a clue?
http://www.aircondition.com/dsmobileac/eatc.html
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