Question about 2005 Chevrolet TrailBlazer

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Loss of Air flow control

Ok, my problem is that I have air blowing through the defrost and the floor vents and NONE through the dash. I am still looking for a solution. I talked to a GM tech and he said it was probably the actual Control Unit or it could be an actuator that controls the vent doors. Now the problem I have is their are a total of 5 actuators on this vehicle and 3 of them are very very hard to get to. Should I spend the money on a new control unit or should I tear my dash into pieces looking for the actuators?

Is this a possible vaccum switch issue?

Posted by Anonymous on

  • Anonymous Aug 22, 2008

    I found the problem. It was the the second atuator from the bottom on the driver side which is called a Mode Actuator. It was not the easiest job to do. I had to take the hole dash apart, drop the steering column down onto the floor board and then completely unbolt the dash from the frame of the vehicle to change this actuator. Good news is that the whole job only cost me $80 instead of $850 quoted by the dealer. It took me about 16hrs to do the job though as I wasn't familar with the dash removal procedure. Once I figured it out though, it went pretty smooth. You just need to make sure that disconnect both battery cables before going in to deep or you risk deploying your airbags. Make sure you have plenty of room to work and take notes as to where the screws come out. I had three screws left over and did some searching and found their place in the cosmetics of the dash itself. It is a job but it can be done at home.

  • rg2utg May 22, 2009

    I have the same problem with 2003 Chevy Trailblazer LT. My son changed my battery, I have air coming out on all ducts under dash and in the backseat, but nothing from front dash. The AC worked fine when I took it to him. Went to go home and no dash AC. Nobody seems to know what happened, or how to fix. Can some one please give me some advise?




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I'm having the same problem, I changed my battery yesterday and all of a sudden my dash vents are not working, I've been told its either a relay switch out or a vaccum hose issue, hope you find out how to fix it if I do I'll post an anwser.

Posted on Aug 22, 2008


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