96 FLD 120 / 12.7 S60 Fan Always On

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Jed2009, Sep 25, 2024.

  1. Jed2009

    Jed2009 Light Load Member

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    @Rideandrepair You have any thoughts?

    I also tapped the clutch with a hammer today to make sure it wasn’t stuck since truck has been sitting for weeks.

    Air is going into new solenoid, but not going out from solenoid into fan clutch.
     
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  3. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Do you have access to DDL, Pro Link, etc?

    Donypu have any fault codes?

    Do you have a fan stat, or just a coolant temp sensor?
     
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  4. Jed2009

    Jed2009 Light Load Member

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    Not personally but could take it to the dealer if needed.

    I am not seeing any dash codes flashing.

    Not sure about a fan stat? I do have the coolant level sensor on the surge tank and a water temp sensor somewhere that goes to a dash gauge and it’s working.

     
  5. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    With DDL or a Pro Link you could see coolant and oil temp, and also see what the fan status is (what the ecm is telling the fan to do), which would greatly simplify diagnosis.

    The common issues on a DEEC III are gonna be coolant temp, oil temp, A/C h9gh pressure, and those associated sensors
     
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  6. Jed2009

    Jed2009 Light Load Member

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    Thanks! It’s a DDEC 4 currently but probably the same applies. If I wanted to test the plugs for those sensors and solenoid, what would I look for? To make sure there isn’t a break in the wires that I can’t see.

    The plug going into the fan solenoid I’ve checked and one prong is +12v and the other is -12v. Would I look for the same thing for the two AC drier sensors/switches? To make sure they are getting the right power or whatever.

    I’ve replaced all 3 with new but didn’t fix.
     
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  7. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Coolant and oil temp just check voltage across the plug. Should be 5v. But, any issue there would set either a high or low voltage fault for that sensor.

    Since you have no faults, you're probably not having an issue there.

    You have 12V and a good ground it appears at the fan solenoid, and it's locked in?

    With the key off does the fan spin?
     
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  8. Jed2009

    Jed2009 Light Load Member

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    Sorry I meant if I wanted to test the two AC plugs on top of the drier. As far as the fan solenoid yes one prong has +12 and another has -12. Air going into the solenoid but does not come out of it. With key off, or in accessory, I can’t move the fan seems engaged. But when I was doing the radiator/AC condenser and drier job right before this I was spinning the fan freely during the process…
     
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  9. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Ok. Are you checking for air at the fan clutch, or solenoid. Are you sure your air line didn't get pinched?
     
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  10. Jed2009

    Jed2009 Light Load Member

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    I am checking for air going into the inlet of solenoid for air supply, which there is. Then I remove the outlet air line on the solenoid that goes from the solenoid to the fan, and there is no air coming out of the solenoid/that line. That line is a couple feet long with one union in the middle of it, does not look pinched or anything.
     
  11. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Ok. Single wire solenoid or 2 wire?

    Nevermind, you said 2.
     
    Last edited: Sep 27, 2024
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