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lowreyfarris's avatar
lowreyfarris
Explorer
Jun 18, 2013

Dash vents not working

My class C on a 2007 Chevy Express will not blow out of the dash vents. The temp switch seems to be fine, I can change it from hot to cold, and the a/c will turn on and off. It seems like whatever needs to open to redirect the air is not working. It will only blow from the window (defogger) vents.

Any advice is greatly appreciated.

Thanks in advance
Class C
  • j-d's avatar
    j-d
    Explorer II
    Jun 18, 2013
    I think "Blend" is the door that balances heater core with air conditioning evaporator to produce your desired temperature. Not as sure of the name for "Mode Select" or whatever that part is, but I don't think it's same as Blend. Quite a few vehicles use Electric for Blend and Vacuum for Mode. Default is Defrost, so I'm with the crew that says it's a vacuum problem. Broken hose, cracked vacuum reservoir...
  • _40Fan's avatar
    _40Fan
    Explorer
    Jun 18, 2013
    There you went. I was about to respond to your question in the Tech section when it told me the post was gone.

    I would have thought it was going to be an electronically actuated mode door, but found out it is vacuum operated. So, you either have a vacuum leak, bad check valve or control unit. Not very often do you see a vacuum actuator go bad and sense it won't go to the floor either, I am really leaning towards a vacuum leak.

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