2015 579 air conditioning

Discussion in 'Peterbilt Forum' started by calvinbabb, Apr 30, 2020.

  1. calvinbabb

    calvinbabb Light Load Member

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    Apr 28, 2016
    Trenton, Fl.
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    Air is bunk works great. In cab sux. The temp doesnt change. Always blows semi cool. When I turn the defrost on it will actually warm the cab but if I turn it to feet, chest, anywhere other than defrost, very little air come out. I have to run my bunk ac on high to keep the front tolerable. I've read, possible blend door actuator. Where is it located? I see 3 or four under the dash. Does anyone have a diagram for the 579 ac? Getting pretty aggravated with it.
     
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  3. Flat Earth Trucker

    Flat Earth Trucker Road Train Member

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    Nov 19, 2018
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    I'm wondering if the cabin filter is clogged up.
     
  4. calvinbabb

    calvinbabb Light Load Member

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    Apr 28, 2016
    Trenton, Fl.
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    I change it every 6 months. So no. Also have cleaned the coils.
     
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  5. mhlvc

    mhlvc Light Load Member

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    May 2, 2020
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    Im having a similar issue on my 2016 579. All vents works except the front vents. I checked the fuses and they all seem fine.
    Im guessing its a blend door actuator, but there are 5 of them, so I have no idea how to figure out which one it is.
    Theyre around $100 each
     
  6. calvinbabb

    calvinbabb Light Load Member

    66
    41
    Apr 28, 2016
    Trenton, Fl.
    0
    I know there was a service bulletin from peterbilt on our years due to blend door failure but was for the doors themselves.
     

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  7. stillwurkin

    stillwurkin Road Train Member

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    Dec 2, 2017
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    When i get the dash open, i activate the control on the one not working. Usually the actuator will attempt to open or close the door. Usually its the plastic gears in the actuator that strip out. Other than that possibly unplug each one and test light it as you try to activate it with the control. Worth a try anyway. Also if and when you do get the actuator out move the door by hand and see if it moves easily. The doors sometimes get dust and get hard to move and the plastic gears strip.
     
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