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Sound of air escaping

Discussion in 'Model S: Driving Dynamics' started by tel, Feb 3, 2016.

  1. tel

    tel Member

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    So, I've noticed this issue lately. When starting to decelerate, I can hear the sound of air escaping from somewhere under the car. It's the same sound that you would hear when the pneumatic doors of a bus opens. After I drive for 15 or 20 minutes, though, it seems to go away.

    I emailed Tesla Service - they said that it represents air from the suspension system used to recharge the dehumidifier, but it seems excessive, considering the number of times I hear the noise. There are absolutely no driving issues, and air suspension works fine.

    Anyone else experience this?
     
  2. Gizmotoy

    Gizmotoy Active Member

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    I don't know enough to say for sure, but this sounds really weird. Why is there a dehumidifier? I haven't seen that mentioned before. Air Conditioning by its nature pulls moisture out of the air, but it doesn't need a pressurized air source to function. Further, they sell cars without the air suspension. What's the impact of a system that requires pressurized air from a suspension component that doesn't exist?
     
  3. AmpedRealtor

    AmpedRealtor Active Member

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    This sounds like nonsense to me. There is no dedicated dehumidifier in the Model S other than the AC, which shares no interaction with the air suspension. Do air suspension cars come with an added dehumidifier just for the air suspension system? Maybe, I don't know.
     
  4. trils0n

    trils0n 2013 P85

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    If it happens on deceleration from freeway speeds, it could be the suspension raising to standard from low. That makes a similar sound to what you describe.
     
  5. AmpedRealtor

    AmpedRealtor Active Member

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    May air suspension is completely silent while raising or lowering, there should be no noise.
     
  6. RDoc

    RDoc S85D

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    Mine too, no sound.
     
  7. trils0n

    trils0n 2013 P85

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    My air suspension has had compressor and other noise raising and lowering since day 1. (Every loaner I've had has made the same noises as well.)
     
  8. tel

    tel Member

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    No, I can definitely hear the usual mechanics behind raising and lowering the suspension. That's not what I'm referring to. This is clearly a blast of air, and sounds just like a bus door opening, or the pneumatic brakes on a truck activating.

    This is the reply I got from the service center:
    "The air suspension compressor will occasionally release a burst of pressurized air to regenerate the dehumidifier. It is normal operation for the vehicle to make that noise."

     
  9. Ingineer

    Ingineer Electrical Engineer

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  10. thecloud

    thecloud As rhythm raced inside, the ship came alive

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    I had also wondered what that sound was. Thanks for clearing up this mystery!

    Over more than a year of driving, my car has made this sound about 3 times, and those occasions were all very rainy days. The first time freaked me out, as it sounded like a large truck was coming up in my blind spot and hitting its brakes. This was definitely a loud blast of air, not the normal gentle sound of the air suspension raising and lowering. I've always assumed it was purging water that got into the air suspension, but was never quite sure.
     
  11. Gizmotoy

    Gizmotoy Active Member

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    Whaaaat? I'm pretty sure that more than half the time they just make stuff up. I find it hilarious that this seemingly-ridiculous statement is the one that's actually true, when so many of the plausible things they say are false. Explains why the air suspension needs a dehumidifier and the coils don't.
     
  12. glhs272

    glhs272 Unnamed plug faced villian

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    This makes sense to me. The air suspension has an air compressor. When the air compressor compresses the air it condenses the humidity out of the air. You don't want the water in the air system, because freezing would be a big problem destroying stuff and the potential for corrosion too. So, they need to separate the water from the air, so they use a desiccant. On the equipment I am involved in building, we use a turbo 2000 air dryer, which uses a heated element to keep the system operating below freezing. In our case we have a removable/replaceable desiccant. It appears tesla is extending/regenerating the desiccant (cool!).

    I too have heard this on my Tesla. I was very puzzled as to what this was, until I ran across this thread. I brought up the issue to Tesla a couple times, but they thought I was crazy or had no idea what I was talking about, and I couldn't replicate the issue (it seemed to happen randomly). But this thread gives me a much better idea of what is going on.
     
  13. Camera-Cruiser

    Camera-Cruiser Fully Charged

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    #13 Camera-Cruiser, Feb 4, 2016
    Last edited: Feb 4, 2016
    What is this silent air suspension you speak of? I can hear mine 15 - 20 feet away outside of the car, and easily inside of the car. Plus I get lovely brake booster chatter thrown in randomly too.

    So these noises are not normal? I am not asking in jest.
     
  14. Ingineer

    Ingineer Electrical Engineer

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    Yes, I think most of those guys have no clue. In this forum alone I've probably heard a hundred different things service has told people that is just total BS!
     
  15. AmpedRealtor

    AmpedRealtor Active Member

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    I don't hear any compressed air sounds from my suspension ever. Not once. That's what I'm referring to. Sitting inside the vehicle there is no apparent noise from the air suspension while raising or lowering.
     
  16. Ingineer

    Ingineer Electrical Engineer

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    On every car I've been in you can hear the compressor when it kicks in. Not loud per se, but no mistaking it either. If you are in a relatively dry area, you may never hear the desiccant purge though.
     
  17. AmpedRealtor

    AmpedRealtor Active Member

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    I live in Arizona so that may be why. Although I had one loaner about 2 years ago that made that loud hydraulic pffft sound several times on the freeway and it scared the bejeezus out of me.
     
  18. Camera-Cruiser

    Camera-Cruiser Fully Charged

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    Sigh. I've got an appointment at the service center this Friday for a variety of things. Tire pressure sensor warnings off and on, noisy air suspension, brake booster pump noise, car lowers randomly when sitting still and no one in car, and some HVAC issues.

    I'm only 90 days into ownership, and it's my second time into service. First was because the passenger airbag sensor failed and the trunk lid was loose. That was 10 days, I wonder what this will be.
     
  19. AmpedRealtor

    AmpedRealtor Active Member

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    Was your car a December 2015 delivery?
     
  20. Camera-Cruiser

    Camera-Cruiser Fully Charged

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    Wow, sorry, I don't why I did not see this until now. No, mine is a 2013 CPO.
     

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