Freightliner Detroit rad fan issue

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by 09DD60, Jun 21, 2021.

  1. 09DD60

    09DD60 Bobtail Member

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    Jun 7, 2021
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    Truck: Freightliner with 14L d60, 450k miles.

    issue: radiator fan is cycling on and off when it is not required. It will cycle on randomly at times, although it seems like it never lets the coolant temps pass 185. It’s keeping the temp between 175-185.
    Even if I’m on the freeway, I will hear the fan kick on for 30 seconds, switch off for 5 seconds and then switch right back on.

    Things to note:
    Does it regardless if ac is on or off (both high and low pressure switches were replaced)

    The only time I have seen the fan kick in appropriately(around 200), was while idling. It never lets the coolant temp reach 200 while driving.

    Fan clutch solenoid was also replaced.

    any input would be appreciated
     
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  3. bad-luck

    bad-luck Road Train Member

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    Is there a loss of power when this is happening?
     
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  4. 09DD60

    09DD60 Bobtail Member

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    I would say yes a slight loss of power, but nothing more than the normal loss of power due to the radiator fan.
     
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  5. bad-luck

    bad-luck Road Train Member

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    Sounds like it could be a loose wire. See if you can jiggle the wires that are running to the Fan solenoid, trace them back move them around and see if this makes the fan cycle
     
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  6. 09DD60

    09DD60 Bobtail Member

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    thank you for the suggestion, I have briefly tried this but will give it a better jiggle today, do those wires lead back to the fuse box?

    is there a possibility it could be the coolant temp sensor on the head?
     
  7. bad-luck

    bad-luck Road Train Member

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    Originally that's what I was thinking, that's why I asked about the loss of power . But I'm assuming you don't have a check engine light. The wires from the solenoid run back to the ECM i believe
     
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  8. 09DD60

    09DD60 Bobtail Member

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    quick update, I jiggled the plug off of the high pressure switch, tripped the radiator fan. Put a bunch of zip ties on it and so far today it’s been good! Will update if issue comes back
     
  9. bad-luck

    bad-luck Road Train Member

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    Glad you found the problem and it was an easy fix.
     
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