2017 Peterbilt 579 Heat not properly working

Discussion in 'Peterbilt Forum' started by ynottrucking, Jan 23, 2023.

  1. ynottrucking

    ynottrucking Bobtail Member

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    I been having trouble with my 2017 peterbilt 579 the heat is not properly working it works when it wants when I start the truck after it gets to 150 small heat blows when it gets to 180 blows Alittle more then after 10-15 minutes it turns Luke warm then to cold I turn it on and off and sometimes it blows hot again for Alittle but back to cold other days won’t blow hot at all and other days it blows hot all day. I replaced the heatercore, hoses, the heater valve and actuator the blend door that controls climate is not broken. Any ideas?
     
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  3. Arctic_fox

    Arctic_fox Experienced mx13 execrator

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    CCU borked. mine did the same thing and pete had to reset the #### computer....because of course they did. Basically they need to calabrate everything. And while i cant be 100% sure it will fix your issues thats what fixed mine.
     
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  4. ynottrucking

    ynottrucking Bobtail Member

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    The CCU? You mean the CECU? The cab computer do you know if they did a software update or flash? I was thinking the hvac controller might be bad but some say no thst part is expensive and it’s on national back order do you know if they used there ESA program to do this? Any help thanks
     
  5. Arctic_fox

    Arctic_fox Experienced mx13 execrator

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    Guy at the pete called it a cab control unit. Basically needed an update and diagnostic done and it cleared up. Again cant say for sure thats the same as your issue but its a place to start since your issue is near the same as mine.
     
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  6. ducnut

    ducnut Road Train Member

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    Unfortunately, all the new stuff is CAN bus. It’s all controlled by computers. You need an update.

    My buddy’s ‘18 579 and my ‘20 T680 have both been updated. Both our trucks started requiring the temp to be set higher and higher, to try and get reasonable heat. After updates, they’ll cook us out, by 78° on the dial. It makes a world of difference.
     
  7. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    CECU update is done with ESA. Even if update does not fix, ESA will point in right direction for proper troubleshooting of your issue.
     
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  8. ynottrucking

    ynottrucking Bobtail Member

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    Ok thank you guys my buddy has the ESA software I will try contact him see if we can run test and update that can control and let’s hope it fixed it out here in Chicago can’t run the truck with this cold weather. I’ll keep you guys updated soon as tests are done.
     
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  9. Arctic_fox

    Arctic_fox Experienced mx13 execrator

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    Honestly the best thing to do is just schedule it to go in every 6 months or so for an update. It fixes a rather moronic number of issues and can usually tell if something is actully having issues or not. Also good to have your AC system deep cleaned once a year or so (i do mine every 3 months as a rock truck and trust me it NEEDS it) it wont get everything obviously but it keeps dirt dust and other nastness from building up and killing your blend doors and actuators.
     
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  10. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    ESA latest update happened last week.
     
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  11. ynottrucking

    ynottrucking Bobtail Member

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    Yes 5.5 from what I heard I have a friend that has it should be able to do it tomorrow hopefully
     
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