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How does the climate control work?

Discussion in 'Model S: Interior & Exterior' started by efusco, Jan 1, 2013.

  1. efusco

    efusco Moderator - Model S & X forums

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    One of the more common questions I've been asked is how the climate control works. Presumably b/c many people realize that there is no engine heat to heat and no belts to run an AC compressor. My canned answer has been that there is a heat pump system, but when pressed for details I have to admit that I don't know any details about how it's set up or how it works and I am curious about the design details of the system.

    Have any of you TMCers seen the system or have any details on how it works?
     
  2. DrComputer

    DrComputer Member

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    I'm pretty sure it's just like in the Roadster. There is a standard electric compressor to feed to AC and a resistive heating element to warm the cabin. Heat pumps don't work in extreme conditions that a car could face (very hot or very cold climates).
     
  3. Doug_G

    Doug_G Lead Moderator

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    I've been monitoring the HVAC power consumption in different situations and it looks to me like it has both resistive heaters and a heat pump. The reason I say this is that the amount of heat being produced (at full defog power) doesn't always seem to correlate with the amount of power being drawn. I'm thinking that it switches to a resistive heater when things get too cold.

    I'm sure Tesla doesn't feel obliged to share technical details of the system, but I am trying to get some idea of how things work so I can better understand impacts on range at cold temperatures. A common trip I do has a 300 km leg with no charge stations en route. I've done the trip successfully at -12C but would like to know how it would go at -25C before attempting it under those conditions!

    And yes I've factored pack heating out of the equation by turning the HVAC off and observing the difference in power draw.
     
  4. strider

    strider Active Member

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  5. ElSupreme

    ElSupreme Model S 03182

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    I had a heat pump in my childhood home in Tampa (perfect climate as it doesn't really get below freezing ever). We had resistive coils also as a supplement, a 'emergency heat' light on our thermostat lit when the coils were running. They turned on right when you turned on the heat (and the heat pump had not run in a while) to give instant heat, and were also used to heat the house if the Heat pump had to defrost itself (or otherwise wouldn't provide heat to the house).
     
  6. MikeK

    MikeK R#129, TSLA shareholder

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    Several people have said it's a heat pump. But at a Tesla event at Menlo Park awhile back, I asked a Tesla engineer, and he said that it was a conventional A/C compressor and a resistive heater.

    I would sure like to have an authoritative answer from somebody who actually works on the climate control system.
     
  7. 100thMonkey

    100thMonkey Member

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    I hope you are wrong. the heater on the Leaf eats range and I've been looking forward to a heat pump with an upgrade to a Tesla S. I will, however, sorely miss the heated steering wheel on the Leaf, it makes "range mode" driving much more efficient and comfortable.

     
  8. Doug_G

    Doug_G Lead Moderator

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    Surprisingly, I have yet to feel the need to wear gloves while driving the Model S. The steering wheel is remarkably comfortable on the hands in cold weather. It's like it is insulated or something...
     
  9. dsm363

    dsm363 Roadster + Sig Model S

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    I agree. 10 degrees here today and no problem with steering wheel temperature. With mobile app coming out will be even less of an issue.
     
  10. mknox

    mknox Well-Known Member

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    Another feature you don't miss if you've never had. A heated steering wheel was not an option when I bought my car, but newer models have it. I had a loaner last time my car was in for oil and tire rotation and boy, was the heated wheel nice.
     
  11. steve841

    steve841 Active Member

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    This is actually a very funny topic.... How is it so many people think since its electric and no engine=no hvac?

    Then when you ask how their house cools down without a V6 motor out front, they slowly start to put it together...
     
  12. woof

    woof Model S #P683 Blue 85 kWh

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    The wheel itself is okay (I'd like it heated too, however), but the chrome strip on the face of the wheel gets mighty cold, and I find that I brush my fingers against the strip sometimes...brr.
     
  13. efusco

    efusco Moderator - Model S & X forums

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    Who thinks there's no HVAC? I've never heard anyone suggest that. The question is what sort of HVAC system is being utilize.
     
  14. steve841

    steve841 Active Member

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    Seriously, Ive had two people ask me if it had A/C .... One simply could not comprehend ... kept asking "How does the compressor run" ..... funny.
     
  15. efusco

    efusco Moderator - Model S & X forums

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    Wow, Ok, once again I've overestimated the average intelligence of the man on the street....I'll never learn!
     
  16. steve841

    steve841 Active Member

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    And one of those was a physician .... admittedly 80 years old, but still a physician. The other, a cop.
     
  17. ChadS

    ChadS Petroleum is for sissies

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    Over the years I've had hundreds of people ask me about HVAC in my EVs. The ones that know nothing at all about EVs tend to ask something like "does it have AC and all that?" They seem to think it's not a real car, and so doesn't have real car accessories - they are the "golf cart" people. You know, the ones that are surprised when you shut the door and it "sounds like a real car". They will typically follow up with more golf-carty questions, like "can it make it up a mountain pass?" Yes, they ask that about my Roadster after I tell them the 0-60 time. (This type of question does seem to be less frequent than it used to be, thank goodness).

    Ones that know a little bit will tend to furrow their brows as they are thinking, and ask something more like "how does the heater work?". They know it probably has one (but aren't always sure!), and they know it requires power...they typically follow up with questions about how it affects the range. They usually think the impact is much larger than it is; as if they expect to get well under half the EPA range in winter. They've read about that on the internet, of course.
     
  18. Doug_G

    Doug_G Lead Moderator

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    Ask them how their home refrigerator or air conditioner works...
     
  19. ZsoZso

    ZsoZso Member

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    Is there a way to turn off the heating ?
    In the climate controls I can turn off the A/C, but I found no way of manually turning off the heater.
    These mornings with the outside temp around 8-10C, the car starts heating, but I do not want that. If I lower the desired temperature it goes to 17.5 then LOW, but I am still OK if its onl 16C inside, I still do not want to heat. I could turn off the whole climate control, but I do like to have the fan working to have some air circulation -- just neutral circulation, neither heating nor cooling.

    In my iMiev even in winter I was usually running with just seat-heater on.
     
  20. mknox

    mknox Well-Known Member

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    There's a whole thread (or at least a long discussion inside of another thread) about this. Short answer: No
     

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