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  #1  
Old October 17th, 2008, 21:48
originalxj originalxj is offline
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HVAC Controls

Real quick question-

I had the A/C on today (It's still warm here in NorCal) and the cool air would periodically blow from the defroster, then switch back to the vents, then switch back to the defroster, etc. Also I noticed yesterday driving with the vent off and windows up I could feel air coming thru the vents. What gives?

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  #2  
Old October 18th, 2008, 07:36
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Saudade Saudade is offline
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Re: HVAC Controls

You have low vacuum or maybe even a vauum leak.
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Old October 18th, 2008, 22:23
originalxj originalxj is offline
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Re: HVAC Controls

A vacumn leak from where? Just anywhere or in some sort of HVAC control?
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Old October 19th, 2008, 07:18
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Re: HVAC Controls

You have dedicated vacuum circuit that provides a vacuum source for the vents and your cruise control (if you have this option). There is a plastic bottle behind the front bumper, passenger side that's a reservoir along with a number of lines that run to it under the battery shelf.

If you have a pretty bad leak, the vents pretty much always stay on defrost and your CC won't work. A slower leak causes the vents to flip around during periods of low engine vacuum like hard acceleration or climbing a hill.
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Old October 19th, 2008, 17:57
originalxj originalxj is offline
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Re: HVAC Controls

OK - at least now I've got an idea of where to start. I relocated that vacumn bottle years ago, I'll have to remember where I put it or just go looking for it.

Thanks for all your help!
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Old October 19th, 2008, 19:58
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the_weirdo the_weirdo is offline
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Re: HVAC Controls

This is most likely due to corroded vacuum lines. I pulled all my hard plastic lines and replaced with 3/8 fuel hose - the problem is fixed and shouldn't return. The worst spots for the hard plastic lines are near the battery and at the firewall under the drivers feet.
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