2020 Pete 579 - Paccar - A/C unreliable

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by StarfireHunter, Jun 14, 2021.

  1. StarfireHunter

    StarfireHunter Bobtail Member

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    Jun 14, 2021
    0
    2020 Peterbilt 579 w/ a Paccar Engine

    The air conditioner randomly decides to not work when starting the truck up.

    I have to shut the truck off, turn off all lights, external lights and wait for the truck to completely shut off (except the eld)
    By shut off, the brain of the engine has to shut off.


    Then I can restart the truck, if it does not blow cold air, I have to repeat the above.

    I repeat this multiple times sometimes until the air finnally works again.

    Then as long as I don't shut the truck off the air works without issues, but if I shut it off, the issue has a chance of arising again.

    For example, my co driver (wife) shut off the truck twice today with no issue, on the 3rd time she fueled, when we restarted the truck it didn't have air conditioning, I had to sit there and do the above method 5 times in the fuel Isle since I couldn't park anywhere else due to it being full.


    Any idea what could cause this, and if there is a way to fix it, this is our last month with this truck and company and I really don't want to have to put it in the shop and spend and entire week waiting on it
     
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  3. Goodysnap

    Goodysnap Road Train Member

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    Hit your nearest dealer and have the HVAC software updated. Version 109 has a fix for intermittent AC clutch engagement. Being a 2020 model your unit may allready have the version, but I would check this first. While they are in there the tech can see if any faults are logged.

    After that, ask the dealer to show the tech one on one, what is happening. Be ready to show him thats its broken and be able to get it to not work. This is the best chance at locating the problem in short order.

    HTH
     
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  4. StarfireHunter

    StarfireHunter Bobtail Member

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    Jun 14, 2021
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    My biggest issue is i can't always reproduce the issue. It's random. I've had months of it working, then one day it just goes off for no reason. Then after many restarts it works again. I've brought the issue up before at a dealer but they can't fix it if they can't reproduce it. Which tbh is so annoying.
    Back then I brought it to them during the warranty, now I think I'm past the warranty period for those kinds of repairs, of course the issues would wind up happening more often AFTER my warranty expires.

    Edit: I'm a lease Operator so all the expenses fall on me, I'm just trying to get through this month and I'm done with this company and this truck.
     
  5. Goodysnap

    Goodysnap Road Train Member

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    Welcome to my work day. Constantly trying to reproduce intermittent complaints. Some you get, some you don't.

    Good luck
     
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