Ho to test /trigger HV battery fan

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Victorio Mo, May 27, 2026 at 9:30 PM.

  1. Victorio Mo

    Victorio Mo Member

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    I just cleaned my fan and want to test it, it's kind hard to hear it, I learned that there are 3 speeds for fan,
    Right now I start driving with outside temp and on the peak have 104-107F with outside temperature 85.

    Is this good indication that fan is working ?
    Or maybe I can try to see if any flow inside vent, with smoke ?

    Best
    V
     
    #1 Victorio Mo, May 27, 2026 at 9:30 PM
    Last edited: May 27, 2026 at 10:46 PM
  2. PriusCamper

    PriusCamper Senior Member

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    It's two wires and fan will spin if you hook those up to 12volts, or even 6 volts. Alternatively you can use Hybrid assistant app via a $20 OBD2 code reader.
     
    #2 PriusCamper, May 27, 2026 at 9:39 PM
  3. Victorio Mo

    Victorio Mo Member

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    Thanks PriusCamper,
    this is too simple test, I tested fan after cleaning on my lab power supply, it's working .
    But when you hook it into the car, it wont' run all the time, need bright temp higher, and then it's still hard to see/hear anything.

    Do you think it should run when PriusDoctor shows 105F?

    V
     
    #3 Victorio Mo, May 27, 2026 at 10:49 PM
  4. Brian1954

    Brian1954 Senior Member

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    An easy way to test if the hybrid battery cooling fan is running is to use a tissue or piece of paper and place it on the intake vent. If the paper or tissue is sucked towards the intake, the fan is working.

    FYI, the fan can run at 6 different speeds. It is very difficult to hear the fan running at speeds 1 to 3.
     
    #4 Brian1954, May 27, 2026 at 11:01 PM
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