Fan won’t shut off on a C15 cat

Discussion in 'Peterbilt Forum' started by Perchie15, Jan 7, 2022.

  1. Perchie15

    Perchie15 Light Load Member

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    Aug 16, 2021
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    Yup I’ve done that for longer that is to
     
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  3. Perchie15

    Perchie15 Light Load Member

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    Aug 16, 2021
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    I had unplugged that sensor and was still nothing and thrown me a engine code. When I did not 100% sure it was the intake sensor tho cuz that’s not the code that popped up
     
  4. Perchie15

    Perchie15 Light Load Member

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    Aug 16, 2021
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    I did wait for atleast over 3mins when I jumped the high pressure ac switch which is right above the rad right? I notice there was some switches in the ac lines along fire wall not sure what they were tho. Gather one was the low side? And no the computer just kept saying fan was on if that’s what u mean? When I pushed the fan override then it’ll pop on computer it was on or off
     
  5. Goodysnap

    Goodysnap Road Train Member

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    Jul 12, 2017
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    You need to monitor the AC fan request in the ECM-Something is commanding the fan to stay on. I think you are seeing the Fan on state, which will be on when the fan is. The Fan cycle switch goes open at high pressure to turn the fan on. So an open circuit will result in a fan on condition. Pull test the wires for being broken inside the insulation. Ohm the wires from the switch to the ECM. You are checking the correct one on the Rad. Should be a orange switch?
     
  6. Perchie15

    Perchie15 Light Load Member

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    Aug 16, 2021
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    Yea it’s orange. Jumped the prongs together n left it idle for awhile n nothing happened. Then the intake temp sender is on drive side above air compressor roughly? That’s what google showed me. I did find rubbed my though loom but wasn’t it. I’ll have to tackle it tomorrow n see. Any other switches that could be setting it to stay on?
     
  7. Goodysnap

    Goodysnap Road Train Member

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    Jul 12, 2017
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    AC fan cycle switch and Cab manual On/off switch are most common. Cant think of any others at the moment
     
  8. Perchie15

    Perchie15 Light Load Member

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    Aug 16, 2021
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    Thanks all for the help!!! Found a broken wire
     
    Goodysnap and Roger McG Thank this.
  9. maconhadalata

    maconhadalata Light Load Member

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    Dec 11, 2014
    newark, nj
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    mine had the same problem...easy fix
     
    bad-luck Thanks this.
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