HVAC high pitched continuous beeping

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by max451, Mar 15, 2018.

  1. max451

    max451 Junior Member

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    Recently I've been hearing a tone while driving. From memory it is about 5,800 Hz (very high pitched, use a frequency generator website to compare). It isn't very loud but can be clearly heard over the radio and other noise.

    Turning the HVAC off immediately stops the noise, and it takes a while to return. Any ideas what this could be?
     
    #1 max451, Mar 15, 2018
  2. bisco

    bisco cookie crumbler

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    does it make the sound while parked with the a/c on and the engine off?
     
    #2 bisco, Mar 15, 2018
  3. max451

    max451 Junior Member

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    I'm not sure. I keep the AC in auto mode for humidity, but it's been cold. I believe the noise has happened with the engine on and off.
     
    #3 max451, Mar 15, 2018
  4. bisco

    bisco cookie crumbler

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    you'll probably need to do some testing to isolate it. try listening from inside the car with windows up, outside with hood closed and then open.
     
    #4 bisco, Mar 15, 2018
  5. William Redoubt

    William Redoubt Senior Member

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    You might want to see if it changes with the fan speed. If so, it could be a vibration from accumulated dust. Also, cycle all other controls when you hear it. Does switching recirculate on or off change it?

    It also might be a noisy electronic control. I have a LED lighted whip that I made for my motorcycle using a cheap controller and it has a nice little ringing tone. But for about $3 I don't care.

    The last thing that might be obvious might be the scroll compressor. Maybe a bearing?
     
    #5 William Redoubt, Mar 15, 2018
  6. William Redoubt

    William Redoubt Senior Member

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    Bisco is right. And if it only happens when driving, the surest way to isolate if from outside with the hood closed is to strap your wife to the hood and have her listen. While it sounds dangerous you can be sure you won't get hurt -- she might, but you won't.
     
    #6 William Redoubt, Mar 15, 2018
    RCO, booke02, max451 and 1 other person like this.
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