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AC Fans

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by rhsanborn, Jul 1, 2018.

  1. rhsanborn

    rhsanborn Junior Member

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    My 2010 Prius had been having problems with the air conditioning. It works fine if the car is moving. If I'm in traffic, it warms up. When the AC cycles on, I see the driver side fan kick on. Are both fans supposed to run? I'm trying to figure out if it's a bad fan, or something like the AC amplifier...
     
    #1 rhsanborn, Jul 1, 2018
  2. Raytheeagle

    Raytheeagle Senior Member

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    Some questions:
    • Any dash lights on?
    • Recent maintenance work?
    • Any recent other oddities or damage?
    • How many miles on your Prius?
    Good luck and keep us posted (y).
     
    #2 Raytheeagle, Jul 1, 2018
  3. ChapmanF

    ChapmanF Senior Member

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    In answer to your question, yes, both fans should run. They are wired in a clever way to have two speeds: both in series (both fans run at low speed) or both in parallel (both fans run at high speed).

    If one fan is open-circuited in some way (either the fan itself or wiring/connectors to it), the car's choices go from (off, both fans low, both fans high), to (off, off, surviving fan high).

    As you might guess, that wiring is interesting enough that the wiring diagram helps a lot when trying to troubleshoot it. Though you could easily start with a close inspection of the connector for the fan that isn't running.

    -Chap
     
    #3 ChapmanF, Jul 1, 2018
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  4. rhsanborn

    rhsanborn Junior Member

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    Thanks Chap, that's a big help.

    Car has ~190,000 miles, I've owned it since ~38,000 miles 5 years ago. No major work. I did have to replace the inverter coolant pump, but I notice AC warming up at low speed before then.

    If both fans are always supposed to run together, then something is going on there. I'll go find that wiring diagram.
     
    #4 rhsanborn, Jul 1, 2018
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  5. rhsanborn

    rhsanborn Junior Member

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    Thanks for the lead, Chap. I'm not sure I would have found it otherwise. "RDI" didn't stand out to me as a fan fuse. It's one of the fuses in the 3-long red multifuse. It's blown. I'm hopefully getting a replacement today, and hopefully there isn't another reason it's blown.
     
    #5 rhsanborn, Jul 3, 2018
  6. ChapmanF

    ChapmanF Senior Member

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    If I were you, I would proceed on the assumption that there is another reason it's blown.

    -Chap
     
    #6 ChapmanF, Jul 3, 2018
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  7. rhsanborn

    rhsanborn Junior Member

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    You're right, I replaced the fuse today (~$12) and it blew inside of a minute. The fan runs on low speed. It blew on high speed, but ran for a bit before blowing which I think probably means there isn't a short, but that fan is drawing too much current. I think I'm looking at replacing the fan motor.
     
    #7 rhsanborn, Jul 3, 2018
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  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    You might find something in this, Repair Manual excerpt on the cooling fans, removal/install, and troubleshooting:
     

    Attached Files:

    #8 Mendel Leisk, Jul 3, 2018
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  9. rhsanborn

    rhsanborn Junior Member

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    Thanks Mendel, I'm going to go through this before dropping the $ on the new fan assembly, just to be sure. It's a big help.
     
    #9 rhsanborn, Jul 3, 2018
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