Heater Blend Door

Discussion in 'KJ General Discussion' started by tdm5032c, Feb 1, 2020.

  1. tdm5032c

    tdm5032c New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Dec 14, 2015
    Location:
    Richland
    I've researched this and found quite a few posts on the blend door actuator and how to replace it, but does anyone know how to repair or replace the blend door itself? Can it be done without disconnecting the AC?

    I got the dash pulled out far enough to remove the blend door actuator and had a new one to put in it, but i discovered that the blend door itself only moves less than a quarter turn and jams. Won't go to hot. Not sure exactly how the blend door works. Is there a linkage connecting it something else in the box itself?

    Any help or drawings/ schematics of the blend door and system would be appreciated!

    Thanks!

    2003 Jeep Liberty Sport
     
  2. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

    Messages:
    6,699
    Likes Received:
    228
    Joined:
    Oct 24, 2008
    Location:
    B.C. Canada
  3. tdm5032c

    tdm5032c New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Dec 14, 2015
    Location:
    Richland
    I don't think is a vacuum issue as the blend door itself won't physically move all the way. Looking at the drawing in the FSM, it looks like there are two blend doors controlled by the electric actuator and they look like they are connected by linkage, but it's hard to tell for sure. Anybody had this apart before?
     
  4. Billwill

    Billwill Full Access Member

    Messages:
    1,468
    Likes Received:
    123
    Joined:
    Nov 26, 2009
    Location:
    White River, South Africa
    Just to be sure here..various flaps directs the incoming air to the various vents ie. defroster, foot well, side vents.
    This is definitely controlled by vacuum!

    My 2002 Export diesel had the air only coming out of the defroster vents after a service at the Dealers. I turned the Jeep around and the mechanics quickly fitted the small rubber vacuum pipe onto the vacuum Pump which the CRD needs for this action and for the Brake Assist.
    The gassers get this vacuum from the inlet manifold.
    If the tube is not connected, the air flow defaults to defroster vents only.


    Then there are flaps/valves that move around for heat control to change the interior temperature when you adjust the heat setting.
    This is done by a Stepper Motor.

    Download the 2003 Jeep KJ Service Manual here..there are good descriptions on how these units work and Section 8W has the Wiring Diagrams.

    www.colorado4wheel.com/manuals/Jeep/KJ/
     
  5. tdm5032c

    tdm5032c New Member

    Messages:
    14
    Likes Received:
    0
    Joined:
    Dec 14, 2015
    Location:
    Richland

    Thanks for the input, i really appreciate it. All other functions of the hvac control work normally. Inside/outside air and directional control through the floor vents, dash vents, and defrost all work like they should. Just the temperature control doen't work properly. Like i said in the first post, the blend door itself doesn't physically move full travel like it should. All the vacuum controlled parts of the system seem to work correctly.
     
  6. Billwill

    Billwill Full Access Member

    Messages:
    1,468
    Likes Received:
    123
    Joined:
    Nov 26, 2009
    Location:
    White River, South Africa
    Yeah check the Service Manual link that I gave you.

    I seem to remember a post somewhere whereby a new Stepper Motor fitted
    had to be "taught" how to move to the correct position after installation.

    I will try find that post but that was long ago now!o_O