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AC Question

Discussion in 'Model S: Interior & Exterior' started by bigsmooth125, Jun 1, 2014.

  1. bigsmooth125

    bigsmooth125 Member

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    United States
    Vague, maybe dumb, question: Is it better to turn the AC to the lowest possible temperature and lowest possible fan level to achieve comfort, or raise the temperature but turn the fan level up? Yes, I know it depends on the specific temp and fan level but just wondering if there's a general rule. By better, i mean in terms of load on the AC system and in terms of energy usage.
     
  2. shepali

    shepali Member

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    Dec 7, 2013
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    N. Scottsdale, AZ
    I don't know the answer, but am also curious. I usually just leave mine on 'auto' and let it do its thing. But on a recent road trip to San Diego....I was wondering how to best manage the energy usage during my bouts of range anxiety (I did have 'range mode' on).

    The other day, I sat in the car in my garage (while 100+ degrees outside) for about 20 minutes and watched the energy usage with the AC on (69 degrees, all auto). Interestingly....I only lost 1 mile of both rated range and projected range in that 20 minutes, and the kwh used didn't move. And I haven't really noticed a daily increase in energy usage as its gotten hotter (we're now over 100 pretty much every day....). I thought I read somewhere in these forums or elsewhere that AC doesn't draw as much energy as heat. But I would be interested in some stats - particularly for road trips.
     
  3. mgboyes

    mgboyes Member

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    I have no data or evidence to back this up, but I would say that if your requirement is firstly that you be comfortable but also secondly that the car achieve your comfort as efficiently as possible then I think you should pick the temperature you want, put everything on auto, and let it do its thing. Trying to second guess the car's internal climate control logic is almost certainly going to mean consuming more power. Given that the AC system is one of the few accessories in the car that can meaningfully impact range it is reasonable to assume that it has already been designed for efficiency.
     
  4. mknox

    mknox Well-Known Member

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    I have found that keeping the fan speed a bit higher helps a bit. I wish that Range Mode wouldn't limit the Fan to 8 because I think the fan motor in comparison to the heating or a/c system has to be miniscule by comparison. I like the idea of limiting the power to the HVAC system in Range Mode, but please leave the blower fan alone!
     
  5. chickensevil

    chickensevil Active Member

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    This would seem to make sense. Hence why if you ever get a Nest for your home thermostat they will keep the fan on after the compressor kicks off to finish circulating the air out of the vents since the fan energy pales in comparison to the compressor. I would assume a car would work the same way.
     
  6. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    What I do is start at the highest possible temperature [where the A/C will run] and then slowly lower it until it gets to the level I want. No loud A/C noise and even at the highest temperature it's still much cooler than outside. I don't worry about the fan speed. Of course, if I'm plugged in, then I pre-cool the car but that doesn't usually happen in the afternoon when the A/C is needed.
     

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