Fan noise during startup

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Much More Better, Aug 30, 2010.

  1. Much More Better

    Much More Better Active Member

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    I am experiencing a fan noise that precedes the ICE during morning startup. It sounds like a model airplane with a cheap, buzzy propeller. It is not the cabin blower and it comes from the front of the car. It goes for about 10sec and then the ICE fires up, drowning out the fan noise, which I presume fades out. And then I don't hear it again when the ICE shuts off. I also don't hear it at a stop light or subsequent restarts. Seemingly, it only does it after it has sat overnight.

    It wasn't always like this. Nothing has changed in my routine. Build date Sep 09. 10000km.

    Any ideas?
     
  2. qbee42

    qbee42 My other car is a boat

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    Are you sure it's not the brake accumulator pump? That will buzz during startup, or when you open the door in a Gen III.

    Tom
     
  3. Much More Better

    Much More Better Active Member

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    It could be. But the buzz associated with the door opening is separate from this one. This one only occurs in the time between when I press the "Power" and when the ICE fires up, before I put the car into gear.
     
  4. risingsun

    risingsun seeker of the way

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    Does it do it if all the climate controls are turned off as well? (i.e. could it be the A/C compressor?)
     
  5. Much More Better

    Much More Better Active Member

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    Doubtful. I leave my fan on at 2nd lowest setting all the the time. I rarely use A/C and never start with A/C on in the morning anyway.

    I parked at work for 9h today and I didn't hear it on my way home. Admittedly it is far easier to hear it in the garage because there's no ambient noise. I'
     
  6. macman408

    macman408 Electron Guidance Counselor

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    A recording would be worth a thousand words. Bonus points for doing it with the hood open so you can tell roughly where it's coming from.
     
  7. mellowgeorge

    mellowgeorge New Member

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    I have heard the exact same noise with the exact pattern. Definitely not the brake pump noise as I hear that the moment I open the driver door. It is related to climate control as I can turn the climate control off right away (before the ICE starts up) and it dies off, though I need to repeat this to make sure.

    I normally do not hear it anymore once I've driven and it is really not audible from inside.

    So far, the a/c seems to be cooling normally and a cursory look and poke does not seem to reveal anything obvious.

    update: found a similar thread describing the same noise, it seems to be normal.
    Strange Noise from A/C Fans - Is it normal? | PriusChat
     
  8. Former Member 68813

    Former Member 68813 Senior Member

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    i'm sure it's AC compressor. it's on when defrost is on.
     
  9. chrisj428

    chrisj428 Active Member

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    I second the a/c compressor -- the compressor is electrically operated and will function at different speeds (and noise levels), based on demand.
     
  10. LulzChicken

    LulzChicken Prius Enthusiast

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    It's more than likely normal.
     
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