1994 Pete 379 Defrost not working and actuator replacement

Discussion in 'Peterbilt Forum' started by staceydude, Nov 7, 2020.

  1. staceydude

    staceydude Road Train Member

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    Hey All,

    I have a 94 379 with the slider style AC which uses air pressure for the actuator in HVAC system.

    The unit and the actuator were all leaking air. I was not able to source the HVAC controls part from peterbilt as it was obsolete, so I took the slider off a Mack part and adapted it to the Pete. That fixed one air leak.

    I also replaced both the actuators in the following pictures as they were both cracked and that fixed those three leaks.

    Now everything works except defrost. Is the lever in the following photo for the defrost diverter door? It is stuck and won’t move.

    how do you get to it? Remember it is 94 and under with the slider style AC.

    any info appreciated.

    also, I wanted to thank this board as this is where I found the part numbers for the actual actuators to order and you can see both of them were cracked. I had air leaks at HVAC controls, and air leaks at each actuator to the point if I got pulled into a scale would probably get a bag fat OOS.

    Thanks

    69A007ED-8623-4251-B7D2-A43692362B70.jpeg
     
    Last edited: Nov 7, 2020
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  3. staceydude

    staceydude Road Train Member

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  4. staceydude

    staceydude Road Train Member

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  5. staceydude

    staceydude Road Train Member

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  6. 062

    062 Road Train Member

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    That big one blew completely apart on me last winter. I had to move the selector just off defrost to keep from dumping all my air. I’ll look tomorrow and see how far it throws it for defrost.
     
    blairandgretchen and staceydude Thank this.
  7. staceydude

    staceydude Road Train Member

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    I appreciate it. When I disconnected it that lever feels stuck. I have air in floor, and vents, but no defrost at all but a tiny amount. Getting into the time of year to not be cruising with no defrost lolol.

    I do hear doors moving around like crazy but nothing on defrost. I see it try to move but it doesn’t .

    I am going to order both those parts just to have them on hand. But I sure don’t know how to get to that door yet.

     
    blairandgretchen Thanks this.
  8. 062

    062 Road Train Member

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    574C93DF-AACA-4B94-9C0E-EF98C3C84DA7.jpeg Hard to get a good pic. Defrost both actuators are retracted. Heat big actuator is extended. Ac big actuator retracted and small extended. As for how to get to the doors???? @pushbroom @wore out
     
    staceydude Thanks this.
  9. staceydude

    staceydude Road Train Member

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    Hey @062 huge help man I really appreciate it. If you need anything and I can help please reach out.

    I am headed over right now to check it out.

     
    062 Thanks this.
  10. pushbroom

    pushbroom Road Train Member

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    This should be the manual for your system
     

    Attached Files:

    RocketScott, 062 and staceydude Thank this.
  11. staceydude

    staceydude Road Train Member

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    Hey Yall, I so much appreciate yall with the photos and the manual. I have it working 100% now, now leaks that my lil sniffer can hear and I am #### happy about that.

    Thanks @062 and @pushbroom !

     
    blairandgretchen and 062 Thank this.
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