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Fan Wiring Help

Discussion in 'Volvo Forum' started by nasriza, Aug 11, 2016.

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  1. Aug 11, 2016 #1
    nasriza

    nasriza Road Train Member

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    Hey guys, so I have a head scratcher. This is the problem i have a 2001 Volvo d12 in my shop having issues with the a/c finally figured out what the problem is. A/C is shutting off because the APADS is seeing high side pressure being at 300 psi and fan is not coming on so it's shutting down a/c system all together. I know it's not high side switch already tried that, it's not APADS already tried that as well. I have it narrowed down to wiring between apads and VECU or ECU, the problem is I do not have access to any diagrams for that side, so I was hoping some of you could chime in if you had this kind of issue before or if you can get wiring diagrams.
     
    nasriza, Aug 11, 2016
    nasriza, Aug 11, 2016
    #1
    rollin coal and mp4694330 Thank this.
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  3. Aug 11, 2016 #2
    CoyoteExpress

    CoyoteExpress Medium Load Member

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    oki i be with you and sing the Song " You are not alone"
    but my one is a 2012 780 :(
    i try to stop nose in and open the hood for better airflow ..
    i think about a manual fan switch
     
    CoyoteExpress, Aug 11, 2016
    CoyoteExpress, Aug 11, 2016
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    mp4694330 Thanks this.
  4. Aug 11, 2016 #3
    nasriza

    nasriza Road Train Member

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    this kind of problem I haven't seen in almost 10 years of working on volvo. other fan issues usually are very easy to figure out whats going on with your fan
     
    nasriza, Aug 11, 2016
    nasriza, Aug 11, 2016
    #3
    KB3MMX and mp4694330 Thank this.
  5. Aug 11, 2016 #4
    QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    Correct me if I am wrong, but a 2001 won't have a vecu? That trigger wire for the fan should be direct from engine ecm to apads correct? I ran into this before years ago so I will check my notebook at work tomorrow and hit you back.
     
    QUALITYTRUCK, Aug 11, 2016
    QUALITYTRUCK, Aug 11, 2016
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    KB3MMX and mp4694330 Thank this.
  7. Aug 11, 2016 #5
    nasriza

    nasriza Road Train Member

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    Im not so Sure if it does or doesnt usually when i get into wiring problems without a diagram i don't even try cuz it turns out to be a waste of time and i have no access to anything on this #### truck
     
    nasriza, Aug 11, 2016
    nasriza, Aug 11, 2016
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  8. Aug 11, 2016 #6
    BoxCarKidd

    BoxCarKidd Road Train Member

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    Please post serial number.
     
    BoxCarKidd, Aug 11, 2016
    BoxCarKidd, Aug 11, 2016
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    KB3MMX and mp4694330 Thank this.
  9. Aug 11, 2016 #7
    benrab

    benrab Medium Load Member

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    On version 1 truck, only Volvo engine have VECU Cummins engine don't.
    Some quick test sir ,
    with engine running if you disconnect the Apad's plug harness the engine fan suppose to turn ON.
    If not, check in EECU (Vehicule Test Information) SUB system for ON -Off air fan Option OR VIscus Fan Option , viscus fan in that year don't have any interaction with the VECU.
    With the truck S/N check if the fan clutch installed match with what you see on the truck.
    In those system (Apad's Modul) wire 682 (by memory) is connected from the Apad's to the VECU, the VECU is requesting to the EECU via J-1939 to turn the fan ON under normal operation.

    About the Apad's system
    The high pressure switch is a 300 N.C. (Normally close) but inside of that switch there is a resistor of (2490 ohms by memory) but when the high side of the A/C system is below 300-325 psi you cannot read the internal resistance with a multimeter.
    The Apad's module send a 5 volts signal to low pressure and high pressure switch and the resistance inside of the switches give a residual voltage in the circuit when to switch come open.
    Hope it can help, let me know the result of your quick test please.
    Ben
     
    benrab, Aug 11, 2016
    benrab, Aug 11, 2016
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    KB3MMX, mp4694330, QUALITYTRUCK and 1 other person Thank this.
  10. Aug 12, 2016 #8
    QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    romulus,mi
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    I am sorry Nasriza. Checked all of my notes and could not find what I was seeking. If I recall (many years ago) problem was in ECM harness not far from ECM connector. Good luck.
     
    QUALITYTRUCK, Aug 12, 2016
    QUALITYTRUCK, Aug 12, 2016
    #8
    mp4694330 and nasriza Thank this.
  11. Aug 12, 2016 #9
    nasriza

    nasriza Road Train Member

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    Chicago, IL
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    thanks for all the help guys
     
    nasriza, Aug 12, 2016
    nasriza, Aug 12, 2016
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    mp4694330 Thanks this.
  12. Aug 13, 2016 #10
    Pablo-UA

    Pablo-UA Road Train Member

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    Borispol, Ukraine
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    Hello

    Really Fan may be switched on by VECU comnand via J1939

    How VECU gets info to turn fan on? There are two ways - auxillary input and J1939 message from Climat unit.

    but these Behr units sometimes wond sending message and we used to run wire to VECU fan.

    Volvo terminal 3948725, pin PA19 (green connector).
     
    Pablo-UA, Aug 13, 2016
    Pablo-UA, Aug 13, 2016
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    mp4694330 Thanks this.
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