Vent control not working

Discussion in 'Ask An Owner Operator' started by Varinderkahlon, Oct 20, 2021.

  1. Varinderkahlon

    Varinderkahlon Bobtail Member

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    I have 2016 Peterbilt 579. The air vent is just blowing air from the front vents. Air does not comes from the windshield vent and floor vents. I tested both the actuators, they are working fine. But i found that the air door pivot which is rotated by the actuator is stuck. Any knows how can i free it? Its vey hard to reach there.
     
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  3. Goodysnap

    Goodysnap Road Train Member

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    There is 5 actuators in the dash total for HVAC control. All actuators are the same part so swapping is possible. Actuators with date codes of 365/15 and older had issues with internal shorting and are prone to failure. Both the temp and panel doors can strip where the actuator goes in or the female splines can break of the doors. These 2 doors are availae seporate, but complete dash removal is required to split the case to replace them.

    Actuator self tests and fault codes are available using ESA and connecting to the CECU.

    If you would like a map of the actuator locations let me know and I will put it up in the morning.
     
    SteveScott Thanks this.
  4. SteveScott

    SteveScott Road Train Member

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    Holy crap, did you ask the right person or what?
     
    mwhjr1988 and Goodysnap Thank this.
  5. Varinderkahlon

    Varinderkahlon Bobtail Member

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    Thank you so much for your reply. Please put the map of actuator locations if you can. I will be very grateful.
     
    Goodysnap Thanks this.
  6. Goodysnap

    Goodysnap Road Train Member

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  7. Varinderkahlon

    Varinderkahlon Bobtail Member

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    Goodysnap Thanks this.
  8. Varinderkahlon

    Varinderkahlon Bobtail Member

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    I have checked all of them. They all are moving fine. I guess the problem is with the central automatic climate control unit that controls all of it. Another thing i am noticing that blower turns on and off itself even when i am on manual setting.
     
    Last edited: Oct 21, 2021
  9. Goodysnap

    Goodysnap Road Train Member

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    Get hooked up. When the blower cuts out you have an active fault.
     
    Varinderkahlon Thanks this.
  10. Goodysnap

    Goodysnap Road Train Member

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    Occasionally I have found the wiring to the HVAC actuators rubbing and shorted to the RR corner of the radio case. Over time the vibration rubs thru the insulation on the wires and shorts them to ground intermittently.

    If you suspect one door or determine 1 is at fault. Remove the actuator and check the slines in the door for being broken/stripped. Put a stubby flat blade screwdriver in the splines and feel for the weight of the door to fall and seal. Dont apply pressure just slight turn both ways about 90 degrees.

    By your description Id focus on the Panel door without hooking up.
     
    Varinderkahlon Thanks this.
  11. Varinderkahlon

    Varinderkahlon Bobtail Member

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    I have found the issue. The panel door is broken. The panel door hinge was not aligned with the hvac box. When I touched it with my finger it droped inside. Is there anyway i can fix this door or have to replace the whole hvac unit ?
     
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