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Help Diagnosing Noise, Prius Shaking/Reverberating -- Invertor?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriusMan5, Oct 11, 2017.

  1. PriusMan5

    PriusMan5 New Member

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    Hi everyone,

    Prius currently has 206K miles on it. I am dealing with this sound.




    When car is park and the gas is pressed, sound does not present itself. When air conditioning or heating is turned on in park the rattling occurs.
    The sound presents itself consistently when car is in motion, this is independent of acceleration.

    At speeds over 70MPH the sound in unbearable, both reverberating the car and causing noises that are unbearable without airplugs.

    This sound appeared roughly last week, and has consistently gotten worse since.

    I am very grateful for your help.
     
    #1 PriusMan5, Oct 11, 2017
  2. exstudent

    exstudent Senior Member

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    I'm voting AC compressor.

    You are throwing TWO possibilities as the cause: air conditioning or heating. Learn to eliminate variables by testing each suspect cause independently.

    RULE OUT Heating
    1. make car READY.
    2. turn OFF AC
    3. turn on ventilation fan (speed irrelevant)
    4. direct anywhere but windshield
    5. put temperature to heat
    6. Does your sound come on?
    7. If NO, then step on gas. Does sound now come on? If still NO, HEAT is not the cause of sound.
    RULE OUT AC
    1. make car READY.
    2. turn ON AC
    3. turn on ventilation fan (speed irrelevant)
    4. direct anywhere but windshield
    5. put temperature to cold
    6. Does your sound come on? If YES, then AC related. Could be the compressor.
    7. Step on gas. Is sound still there? If yes, AC related.
    If it is the compressor, find a competent AC person who knows how to work w/ Toyota's electrical AC system. Many hacks out there.
     
    #2 exstudent, Oct 12, 2017
  3. PriusMan5

    PriusMan5 New Member

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    Thanks for the input. My question is as follows:

    How can it be the compressor if the sound occurs when the car is in motion and the AC and/or heating is not on? I thought this was the compressors only function.

    I will try the tests you laid out above in the morning.
     
    #3 PriusMan5, Oct 12, 2017
  4. exstudent

    exstudent Senior Member

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    Read what you said in your original post:

    I would think, most people would share my conclusion of an AC compressor issue, based on the way you described it.

    Slight clarification added from post #2.
    RULE OUT AC
    1. make car READY.
    2. turn ON AC
    3. turn on ventilation fan (speed irrelevant)
    4. direct anywhere but windshield
    5. put temperature to cold
    6. Does your sound come on? If YES, then AC related. Could be the compressor.
    7. Step on gas. Is sound still there? If yes, most likely AC related.
    8. Step on gas. Is sound still there? If NO, something else is amiss, but AC is still an issue.

    Since you don't think its the AC compressor, and your description of cause and effect is far from ideal, rule out: water pump bearing, wheel bearing.

    Hopefully someone else can decipher your sequence of events.
     
    #4 exstudent, Oct 12, 2017
  5. PriusMan5

    PriusMan5 New Member

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    I tested the steps above. My findings are that the sound is only present when the AC is on, but not when the heat is on.

    So yes, it definitely looks like it is the compressor. But I am confused as to why the sound also occurs when the car is in motion and the AC is not on? Is the compressor also utilized while the car is simply driving? And then why is it significantly louder at higher speeds than it is at lower speeds?

    Does anyone have any insight into this?

    Exstudent, thank you for your help so far.
     
    #5 PriusMan5, Oct 12, 2017
  6. exstudent

    exstudent Senior Member

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    There are TWO issues.
    1. AC compressor is most likely confirmed.
    2. The unknown 2nd issue.
    AC compressor is supposed to be engaged when you have the AC button depressed (ON). OFF is off, ON is on.

    Sounds like a bearing b/c the noise is proprotional to speed. Low speed-low sound, high speed-high sound.
    Rule out water pump and wheel bearing.

    Quick easy way to rule out waterpump is remove the belt and with your hand/fingers, turn the waterpump pulley. If you feel any binding, replace the water pump. This might be the source of the speed replated squeal. Also, if there is a lot of dry crusted coolant on the outside of the water pump, replace it, irregardless if the waterpump pulley spins freely, w/o any binding. If waterpump is bad (leaking, bad bearing, both), replace it.

    You will still have to rule out wheel bearings. If the waterpump was bad, and replaced, there should be no additional noise when the car is in motion. If there is a noise with AC off and vehiclw is in motion, wheel bearing is likely culprit. Determine Left/Right/both sides.

    You could be unfortunate to have three issues: AC compressor, water pump, wheel bearing.
     
    #6 exstudent, Oct 12, 2017
    AltraStache likes this.
  7. Jmack111

    Jmack111 Member

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    #7 Jmack111, Oct 15, 2017
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