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84 C10 blower won't come on

Discussion in 'GM 6.2 Diesels' started by Landon730, May 16, 2018 at 5:56 PM.

  1. Landon730

    Landon730 Member

    52
    37
    Aug 7, 2017
    Greenwood Arkansas
    I can't get the blower to kick on and it looks like it was replaced not long ago. (Truck was last on road in 2008 lol) But anyways I THINK its the control head because the sliders feel pretty loose. Checked with a multimeter and we have voltage to the relay under the hood. Had to run a direct wire from a/c compressor to battery to charge the system. Blows cold air out the floor vent but whenever I use the sliders on the control head nothing changes.
     
  2. EWC

    EWC Active Member

    223
    74
    Jun 14, 2008
    Is the vacuum pump working ?
     
  3. 3500GMC

    3500GMC What T F, over

    5,463
    590
    Jun 7, 2009
    Nashport, Ohio
    The blower motor needs a ground and grounds through the flange/case on the motor itself. The fiberglass AC box doesn't offer any electrical conductivity to the cab of the truck. Maybe that's your problem.. ?
     
  4. Landon730

    Landon730 Member

    52
    37
    Aug 7, 2017
    Greenwood Arkansas
    Doesnt have one
     
  5. Landon730

    Landon730 Member

    52
    37
    Aug 7, 2017
    Greenwood Arkansas
    Ill look at it and get some pictures for you tomorrow I didn't think to look for grounds
     
  6. EWC

    EWC Active Member

    223
    74
    Jun 14, 2008
    You need a pump , that is what powers the vents and doors . No pump , no movements .
     
  7. 3500GMC

    3500GMC What T F, over

    5,463
    590
    Jun 7, 2009
    Nashport, Ohio
    Yes^^ The HVAC on these were all vacuum actuated. Could be that the blower motor is doing it's thing but you cannot feel any air from the vents. Can't recall if there's a default position, say defrost only, if the vacuum isn't hooked up.
     
    Landon730 likes this.
  8. Will L.

    Will L. Well-Known Member

    7,406
    6,008
    Jan 25, 2013
    Boulder City Nv
    If you don’t want belt driven vacuum pump, just get an electric one in there.

    If you have a mighty vac test tool or house vacuum with a hose, just rig it temporarily to the main line where the pump was and test if it opens the valves.

    Man I miss when 2 cables controlled everything. Once every 30 years replace a couple $20 cables and only if from a rusty area. Plenty of factory cables in use on rigs around here.
     
    Landon730 likes this.
  9. Landon730

    Landon730 Member

    52
    37
    Aug 7, 2017
    Greenwood Arkansas
    Took the gauge bezel out and firgured out the hvac control head actually came apart. The mode switch litterally fell apart. Put working control head in and its working now.
     
    Will L., smokymtn65 and Jaryd like this.

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