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Thread: HVAC blower fan speed control

  1. #1
    Join Date
    Nov 2006
    Crappieville, USA
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    Default HVAC blower fan speed control

    Post #1
    The HVAC blower fan 5-speed control on my vehicle went to a 3 speed and eventually to OFF or high speed only. Did a little research and narrowed it to be the motor resister control module. Picked up an after market on ebay for 15 bucks shipped ($109 dealer part). Watched a video on youtube and changed it in 20-min tops. 2 (5.5 mm) screws and 2 clips. The old one had rusted and was literally falling apart (surprising high speed worked). If your fan speed control isn't working, don't spend your hard earned cash on a simple fix. Youtube and ebay can save you money to buy more jig

    Post #2
    Here are the pictures from the old HVAC Blower Motor Resistor Control Module

    Recently I had been seeing vapors coming through the vents when the hvac system goes from ice cold AC to just running the vent with the ac off. So there has to be moisture internally. This part is located in the lower portion of vent duct system. It goes to reason that some of the moisture is collecting here and causing the corrosion. The rectangle base of the part is just plastic. Wonder if drilling a vent hole for air circulation would help? or just let it go since this part limped along for 8+ years....

    Hope this helps

  2. #2
    Cray's Avatar
    Cray is online now Legend and Moderator of the Mechanics Forum * Supporter
    Join Date
    Oct 2010
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    You should have a external drain for any moisture in the bottom of the box to the outside of vehical. Just a rubber tube sticking out. Check to see if that is pluged.
    Proud Member of Team Geezer
    Charlie Weaver USN/ENC 1965-1979

  3. #3
    Join Date
    Jun 2009
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    I wasn't able to see the pictures so I don't know what type of vehicle it was. I will say this: Chevrolet had a history of these HVAC modules going bad. Usually one speed will go, then the next. Pretty soon you are stuck with high only.

    I picked a buddy up in Seattle a few years ago. On our way back to Michigan, his truck did the exact same thing. During my nap time, I did some research and found this issue. Funny thing was, my truck did the exact same thing several weeks before hand. We ended up buying two of them from a local parts store.
    I have OCD "Obsessive Crappie Disorder"

  4. #4
    Join Date
    Mar 2008
    Paris Landing, Tn.
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    The reason they continue to work on high is because "high" bypasses the resistor and feeds power direct to the blower.

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