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  1. #1

    Default no air to floor, air blows on windshield

    2000 Blazer. When floor (heater) is selected it blows on the windshield (defrost). Split, floor and defrost, only blows on the windshield. Split, vent and floor, only blows out the vents. All other modes function normally. I have disassembled and cleaned the selector switch (which controls and directs vacuum) no help, still can not get air blowing on the floor. Thanks in advance for any help with this matter, Don.

  2. #2


    You have a vacuum leak. Look under the hood. In my van, the vacuum line that attached to the vacuum reservoir was all rotted and mushy. I changed it and all is good again. I also had a leaking vacuum line going to the purge valve.

    Default postilion in case of failure is the defrost vents.
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  3. #3


    Try using a vacumm pump to act like the vacumm bulb and if you can switch it over that way then bulb bad - this way you can isolate vacumm bulb from vacuum lines or head issue.

  4. #4

    Default Problem solved

    Thanks for the replies. Sorry for the long delay in my response but I didnít get around to working on this project until the past weekend. It was a broken vent (door), part number 52470781, in the heater box for directing air flow to the floor. To replace the part I removed the dash. This was too much fun for 1 person so I had a friend help me lol. We were able to replace the part thru the top of the heater box without having to remove the heater box. Yes it was big job but it all works fine now. See attached picture of broken part. Thanks again.

    Click image for larger version. 

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  5. #5


    That'll do it! Glad you got it sorted out.

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