Question about 2001 Oldsmobile Silhouette

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2001 olds silhouette - no airflow at defrost vent when in defrost

Blower works on all speeds and in all settings.
airflow at panel and floor is ok.
air temp is ok.
cabin filters are clean.
when in defrost mode - blower runs on all speeds but there is no air discharged at defrost vent. Any suggestions appreciated. Thanks.

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  • Falcon15 Jan 10, 2009

    Wiz - when in defrost, no airflow at other ports to speak of.
    Misterwoods - thanks for the insight.

    The servo motor got me thinking. I proceeded to reduce airflow setting to 1 (lowest air-flow), then I moved air flow selector from panel to defrost - waited 5 second (heard the dampers move) - then increased airflow to 5 (highest setting). At that point, I got great airflow through defrost vent. I found that when I move airflow selector from panel to defrost while keeping air flow at 5 (highest setting), the air discharge at pane stops but the airflow at defrost vent remains at zero as well. Could it be servo related or vac line switch/line?? Thanks in advance.



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When you set the Defrost does any air flow from other ports?

Posted on Jan 10, 2009

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On cars anywere from about 92 or so and up, they do not use linkage anymore to move the the flaps that direct the air above or below the dash. Now they all run by electrical servos. What that means is that when you turn the nob, your not actually moving a metal bar to move the system. Your telling a sensor to move the flaps into the position you desire. There could be a few problems here. It could be the electical motor it self, or could be, what Im assuming, a rotory nob, which is actually called a retrostat, is not hitting the proper connections due to wear, or even dust. This may be a problem you want to put up with, becouse to diagnose the problem its self will not be cheap. If the nob is the problem, you have to replace the whole unit its self. Depending, it should run around for your vehical $200 or so. I hope this helps. John...

Posted on Jan 10, 2009

  • John Woods
    John Woods Jan 10, 2009

    FYI, When I said $200 or so, I meant just the part its self. Not diagnostics, or intall of said part.



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