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Normal coolant temp for fans to come on.

Discussion in 'Gen 2 Prius Main Forum' started by kens97uber171, Apr 26, 2019.

  1. kens97uber171

    kens97uber171 Active Member

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    Noticed some large fluctuations in coolant temperature, the fans come on when the AC compressor kicks on but I'm not sure that the fans are kicking on based on engine coolant temperature. Does anybody know at what temperature they normally kick on. I sat in a parking lot with the AC turned off but my foot on the gas and let the engine run hybrid assistant reported 201 degrees at which point I decided that was pushing it far enough picked on the heater and the AC in the temperature dropped very quickly. So I'm suspecting if that is too high of a temperature that the sensor that kicks on the fans is malfunctioning since obviously the fans work. Anybody have any suggestions I would greatly appreciate it

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    #1 kens97uber171, Apr 26, 2019
  2. SFO

    SFO Senior Member

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    Should kick in around 180F, or 82.2C.
     
    #2 SFO, May 5, 2019
    Raytheeagle likes this.
  3. ChapmanF

    ChapmanF Senior Member

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    Pretty sure mine start around 95 C. The people programming the ECUs definitely think in SI units, because you'll usually notice the interesting things happen at nice round Celsius temperatures ending in 0 or 5....

    The fans have a low and a high speed; I don't remember offhand which conditions go with which mode.

    The circuit that gives the fans a low and high speed can have an interesting failure mode, where low speed stops working but high speed still does. If that happens, the fans will seem to kick on and off a lot more noticeably than usual, because they'll be cycling between nothing and high speed, continually around the upper trigger point.
     
    #3 ChapmanF, May 5, 2019
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