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climate control tips and tricks

climate control tips and tricks

Addendum 1/2016 - with software 7.0 and beyond, automatic climate control was significantly improved. Much of what I have posted below is not relevant for current software versions, but I'm leaving my post intact .
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I've spent the last 3 months parsing the climate control. My initial impressions were not positive as it seemed hard to decipher the display and difficult to titrate to a precise temperature. Overall it seemed under engineered compared to other luxury cars. As I've used it, I've come to appreciate that it's actually quite powerful and customizable. Some tricks I've learned:

- temperature and fan speed are independent. In other words if you don't like being blasted by semi-cold air with the fan at 8 and the temp at 68 to get cold, you can manually turn the fan down to 3 or 4 and turn the temp down to LOW. That gives you ice cold air at a low gentle breeze. Given how quiet the car is, it's nice to have the fan speed as low as possible.

- Turning recirculate on automatically drops the indicated fan speed down 1 or 2 but actually almost doubles the air output. Lower fan speed, more air output. It's particularly helpful for cooling.

-the climate control display is quite informative. 1 lit fan blade equals fan speed of 3 or less, as more fan blades light it indicates greater fan speeds (there are 4 total, each represents about 3 fan speed positions). This helps me to judge whether the climate control is working unnecessarily hard, ie if I'm not particularly hot or cold and 3-4 fan blades are lit up, I will take it off auto so it's not working unnecessarily hard.

- as most already know, the display shows you not only fan speed but where the air is being directed (which actually tells you whether it's heating or cooling (see below), and whether it's on fresh or recirculate.

- Air movement arrow at the face tells you it's cooling the interior, arrows at both face and feet indicates it's maintaining current temp, arrows at the feet only indicates heating. I use this to adjust my temperature according to whether I want to feel warmer or colder, rather than trying to guess which temp setting will turn on heating vs A/C.

- best way to get and maintain a very cold interior on a hot day without getting blasted by max fan speed is to leave it on auto for about a minute or two, then hit recirculate, drop the fan speed down to 4 or 5, and set temp to LOW. after a couple minutes I can even drop the fan speed lower. That gives you a quiet, cold interior.

- there are many days in the 50-75 degree range where I turn off climate control for extended periods. It's just not necessary and especially on the colder end of that range, reduces energy use.

Unlike my other cars where I gave little thought to the climate control and just left it in auto all the time, this one requires more driver input. Good for micro-managers and OCD types, annoying perhaps for others.

gwpotter | March 22, 2015

@eye.surgeon

Thanks for taking the time to share this. A couple of your observations I had sort of figured out. But the subtitle things like the number of fan blades illuminated will be very helpful.

Greenee | March 22, 2015

@eye.surgeon

Just printed out your observations. We have had a difficult time figuring out the air also and we are in Palm Springs with 90+ temps. We have had our car for three weeks now and I will play with the air this afternoon. These forums truly do help the rookies like me!

Thanks

Bighorn | March 22, 2015

I think all ophthalmologists have a touch of OCD--thanks for the primer:)

minervo.florida | March 22, 2015

Tinted windows are a must in hot climate, huge difference.. I am in Florida 13 years.

Brian H | March 22, 2015

2C;
Where are the subtle subtitles? Can't find 'em.

Ruizmeza | March 22, 2015

Awesome observations. As a surgeon myself, I can attest to the OCD care for fine detail on Eye's post.

Thanks.

Will carefully test on the hot summer miami weather.

TaoJones | March 23, 2015

Suggest sending the OP to the mothership so that value can be added to their man(ual) pages. Nice work.

I too have been trying to finetune the HVAC these first few months and found myself wondering why once again my previous vehicle, a lowly Volvo, appeared to better functionality in this regard. The findings in the OP will help to close the gap. Much appreciated.

I did get so far In my own tuning efforts as to note that multiple driver profiles can help - for example, having an exit profile that one taps when getting out can prevent an unexpected heated seat and otherwise cool interior when getting back in.

Now if I could only figure out why "smart" preconditioning insists upon activating after 10pm some nights but not others.

Early adoption. Mmm mmm good. I have no problem with the Model S being neither a luxury car nor an exotic car. I just wish someone would tell that to most of the insurance industry.

bp | March 23, 2015

At least for my 2 year old P85, keeping the temperature comfortable requires manually setting the temperature to 67 when it is warm outside and to 72 when it's cold outside.

When that's been done, the car stays comfortable - but in the spring/fall when temperatures shifts between hot and cold - it requires periodically adjusting the temps.

barrykmd | March 23, 2015

eyesurgeon - Don't know how old you are, but I think you would have loved the manual-tuned phaco days :-)

WØQR | March 23, 2015

Where is the sensor for temperature? I would think if you set the temp at 72, the fan/heat exchanger would run until that is achieved with a little 1 degree hysteresis. Anyone know about where the sensor is? It must not be measuring cabin temp.

eye.surgeon | March 23, 2015

I believe the temperature sensor is the quarter-sized perforated area next to the USB plugs under the armrest.

Rocky_H | March 23, 2015

I had also discovered that air conditioning recirculate thing. It's nearly worthless using outside air, unless it's loudly blasting the fan at 10 or 11. Recirc is so much better for A/C, and the Auto mode never seems to want to use recirculate.

I can let it do auto for heat, but I do need to fine tune more for cooling, whether I want to use windows down and climate off, or blow outside breeze with A/C manually turned off, or A/C with recirculate, etc. I actually keep fan speed on my right scroll wheel, because I do use it so frequently.

TeslaTap.com | March 23, 2015

@eye.surgeon - "I believe the temperature sensor is the quarter-sized perforated area next to the USB plugs under the armrest."

While I don't know where the sensor is, I don't think that is it. Older cars don't have the perforated area, and when I asked about it, the tech said it was for better air flow for some electronics in the pedestal. Then again, perhaps it is the sensor and the location changed!

marqdow | March 23, 2015

@minerno.florida
Our local trio of new MS owners on the FL west coast would love to know the details of your window tinting. Thanks

staze | March 23, 2015

Valuable post eye.surgeon! Thanks!

Anyone have any tricks for the heat? Though we are in SoCal, we can never seem to get the car heated quickly enough without placing the temp on "HI" for a few minutes. My wife very much dislikes the heating in the car. Luckily, it's only an issue if we travel in the evenings a few months of the year.

Grinnin'.VA | March 23, 2015

@ TaoJones | March 23, 2015

Now if I could only figure out why "smart" preconditioning insists upon activating after 10pm some nights but not others.Now if I could only figure out why "smart" preconditioning insists upon activating after 10pm some nights but not others.

From the release notes I understand that "smart preconditioning" is an artificial intelligence function that figures out when you typically leave "home" to go to your "work" location and then heats the interior shortly after it thinks you are about to drive from "home" to "work".

For owners who have no 'regular schedule', the fancy AI software is doomed to fail. It keeps trying to figure out when you usually leave "home" to go to "work". But since there is no usual time for you to make such trips, it's forever stuck trying to 'learn' when you're probably going to leave "home" to go to "work".

There is another obvious weakness of "smart preconditioning": It doesn't do anything to heat or cool the battery. In the winter, the car is a bit inefficient (high Wh/mi) until the battery is warmed up. I suppose it might have a similar problem in the summer when it's too hot.

Bottom Line: "Smart preconditioning" isn't smart. It's dumb software focused on solving the wrong problem.

IMO, what we need most is the ability to preheat or precool the battery on user command from the iPhone app. (We can already turn on or off the interior heat/AC via the iPhone app.)

Grinnin'.VA | March 23, 2015

In my first paragraph, I intended to write "before" instead of "after".

minervo.florida | March 23, 2015

For those wanting to know about my tint, it is the same I have used for over 6 years on about 4-5 cars. I get the darkest tint allowed on all windows, this is pretty much what everyone does so they are legal.
Which is darkest on rear window and rear doors, and the 4 inch piece on the front window. The front doors are lighter.
I use a great company in Venice , Razor sharp at 119 Corporation Way unit F in Venice Florida, 941-486-0346. You can watch the whole process, and I drive my car in and out.

All their films are great, top quality, computer cut. Takes my fan speed down about 4 clicks, would never be without it down here.

Hope this is what you were looking for.

My wife's S85 has it, and I will put it on my new P85D coming Wednesday.

Chunky Jr. | March 23, 2015

I started to pay attention to how much the climate control system affects range, and the basic answer for me is "a lot". Maybe 20% or more. When I had climate control on and set at 72, I was averaging about 350 Wh/mi. Several weeks ago I turned off A/C and set temp down to 68, and it is now more like 300 Wh/mi, with many 5 mile stretches in the mid 250s. It's a much bigger difference than I was expecting based on the calculator on Tesla's web site.

Anyone else seeing differences like this when heater or A/C is on vs off?

Tracy_Moody | March 23, 2015

Here in TN, I have tinted the entire windshields of all my vehicles for the last several years (70-75% tint). Cuts down on damaging UV, provides heat rejection, and also cuts down on oncoming glare from other vehicles' lights.

Brian H | March 24, 2015

ChJr;
"heater or AC" are not equivalent. Heater costs a great deal, AC not much.

trixiew | March 24, 2015

I'm so anal I can never decide if the sub optimal aerodynamics of opening my window and sunroof are worse for rated miles than running climate control.

nickjhowe | March 24, 2015

@eye.surgeon - great write up. Some gems in here.
@J.T needs to include these in his FAQ.

EVino | March 24, 2015

- Air movement arrow at the face tells you it's cooling the interior, arrows at both face and feet indicates it's maintaining current temp, arrows at the feet only indicates heating. I use this to adjust my temperature according to whether I want to feel warmer or colder, rather than trying to guess which temp setting will turn on heating vs A/C.

Thanks eye.surgeon. Good tip.

PhatGloves | May 25, 2015

Yes, I notice a significant Wh/mi decrease with any incremental decrease in AC / fan speed. It's quite pronounced in my experience.

J.T. | May 26, 2015

I've added a link to this excellent thread to the Operations section of the FAQ.

WØQR | May 26, 2015

Anybody that can use titrate in normal conversation has my vote! I know what it means and it's well applied in this case. IMPRESSED..great article.

rhbohl | June 9, 2015

BP's comment of "67 when it's warm outside" and "72 when it's cold outside" mirrors my experience. I suspect Tesla put the temperature sensor in an inappropriate location. With my 2001 BMW 3-series, I set the temp at 72 and rarely touched the controls. I'm a bit disappointed that Tesla didn't do a better job in this respect. That having been said, I'll just live with BP's figures, stop being puzzled, and get on with my life.

TomServo | June 9, 2015

The HVAC system in our Volt's works like any other car I've owned, but as many have pointed out use of the HVAC system can kill one's range. In the Volt the AC is far more efficient than the heat. In the winter heater use can kill my range by 25%, use of the AC in summer cuts range by about 20%.

Re window tint, I had both our Volt's tinted to 35% (legal in Illinois) with Llumar ceramic tint worked great in the summer, but in the winter caused me to need more cabin heat due lack of solar heating.

So for folks that experience 4 seasons tinting can be a blessing or curse.

But since I have learned to keep a COOL (some as COLD) cabin temp in the winter I'm inclined to have the windows tinted when Inhet my Tesla.

Grinnin'.VA | June 9, 2015

@ TomServo | June 9, 2015

... use of the HVAC system can kill one's range.

Undoubtedly, AC takes energy, which reduces range.
Today I went on a 150-mile day trip on a hot, sunny day.
By running in range mode and driving at moderate speeds, I made the trip at about 275 Wh/mi. Both I and my passenger were comfortable.

joel | June 9, 2015

Just a point regarding having different set points for heating vs. cooling:

When cooling is required it is often due in large part to high radiant heat transfer (sunlight either directly on the occupant, or on the car which in turn radiates to the occupant). The human body has a high response to radiant energy compared to convective (almost double).

When heating is required it is usually in response to only convective energy, but cooling usually has to respond to both radiant and convective. Radiant conditions can change almost instantly, where convective conditions change more gradually. If the sensor is hidden somewhere tucked out of the way in the car, it is almost definitely only reading convective energy, leaving the user to adjust controls to respond to the body's greater sensitivity to radiant energy.

I strongly suspect that if there was little to no radiant component (no sun or solar radiation) different setpoints for heating and cooling wouldn't be necessary.

Kind of off topic I know (sorry), but an interesting perspective on human comfort.

edwardhart | July 26, 2015

Most of us are accustom to the automatic climate control systems used in modern ICE cars. Tesla, of course must do things differently because of the lesser amount of energy available. So...

In an internal combustion engine (ICE) car, there is a very large excess of heat available from engine cooling. ICE cars use what is called a reheat system; air coming into the car from the cowl (just ahead of the windshield) goes through the air conditioning evaporator and is typically cooled to very low temperatures, say 34-36F. This air is then reheated by passing across the heater core. A simple motor driven door decides how much of the air goes across the heater or bypasses it. The cool and reheated air streams are then blended before being blown into the cabin. The very nice aspect of this approach is that the incoming air is dramatically dehumidified by the cooling - that is the source of the water dripping from under the car - and then reheating to a comfortable temperature. The cabin air is a nice low humidity level, adding enormously to comfort. This is ideal for hot and humid places (Miami), but also nice in wet winter climates (Boston), and that latter is why the air conditioning compressor is running almost all the time....unless you press some kind of ECONOMY button, which turns the compressor OFF. Try it sometime when it is cool and raining to understand the impact.

The same process is in effect when recirculated air is selected, usually called MAX COOLING). In recirculation, about 80% of total airflow is from recirculation with 20% still coming from the outside. That last 20% from the outside is to overcome any exhaust gases that may have leaked into the cabin. (Yes, this was the result of a lawsuit many, many years ago.)

The air conditioning compressor is a big energy user. In an ICE car, it is one of the many accessories driven directly by a pulley/belt system on the front of the engine. This is a highly developed system in ICE cars, and much has been done to minimize the energy consumption. I believe some cars today actually have some form of humidity sensor to minimize how cold the evaporator should be to assure comfort.

Importantly, most climate controlled ICE cars use at least four temperature sensors to assure fast response to changing conditions. First, the outdoor air temperature is measured to help set the overall demand that the system should expect. Next, there is at least one in-car air temperature sensor, usually one at breath level and another under the dash. The latter usually senses aspirated air, taking advantage of blower operation to pull air across the sensor for faster response. There is usually a blended air sensor, too, designed to let the controller know what temperature of air is actually being sent into the cabin. Finally, and very importantly, these systems rely on a sun load sensor, positioned on the dashboard so that it can closely estimate how much sun load the front seat occupants are receiving. With this information, the system can respond very quickly to the climate dynamics. Hold that latter thought, please.

I have an MS 85 and have been looking for more detail on how the climate control system works, so this forum is very helpful. I THINK it is as simple as this: there is no reheat as in a conventional ICE system described above; the Tesla climate control system either heats or cools.
Oh, and there is no heat pump in the Tesla. A heat pump is kinda like running an air conditioner in reverse. The benefit is that it delivers more energy in the form of heat than the amount of energy required to run the compressor. For example, three KW of heat might be delivered for using only one KW of energy. BUT….that is a complexity that Tesla does not need at this time. And…NO….Newton’s Laws were not broken in the making of such machines!
So, as others have pointed out, heating is just a resistance heater for cabin air in combination with the very important seat heaters. Direct resistance heating of the human body is very important for this application.
I am guessing that Tesla has selected a small compressor compared to what is used in an ICE car. That being the case, then it makes sense to keep airflow rates low when drawing in outdoor air to the climate control system, because it takes a lot of energy to continuously cool hot and humid outside air. At too high an airflow rate, the small capacity of the system would have trouble dehumidifying the air. In recirculation, however, the air temperature and humidity coming into the climate control system are much lower after the cabin cools down, thus requiring less energy to keep the cabin comfortable…also meaning that higher airflow rates are possible.
There may be a waste heat reheat capability in the system, but I have not been able to find such information. If anyone knows, I would like to hear from you. Beuller?
For me the net:net is that I put the system in full automatic, then select recirculation mode. It is a bit noisier with the recirculation door open, but I like the higher airflow.
A sore point is, however, that Tesla does not appear to have any sort of sun load sensor. I find that within a few seconds of turning into the sun, I am getting uncomfortable, especially if I am wearing a sweater. HOPEFULLY….someone at Tesla is working on adding such a sensor to future systems.

hybridbear | October 12, 2015

If you're driving in the summer with A/C on but the air temp of the cooler air is determined by the car to be "too cold" for the cabin, will the Tesla turn on the heater as well? That's one of the things that we find most annoying in our current EV, that it decides to run the heat when it's hot outside and burn through a lot of electricity if you aren't careful. I'd hope that the Model S doesn't do that...

pablocasa777@.com | January 5, 2016

Is there a way to set the climate control for operation while the car is off from the car? I can use the Tesla App and do it from my phone or tablet, but there should be a way to set it from the car before turning the car off. It commonly takes 30 seconds or more for the app to connect to the car, and I don't always have my smartphone either.

Living in MT I need heat more than range, and keeping the car dry inside is a real challenge so I need to leave the heater on sometimes. Overall, the heater kicks butt, super impressed with how quick the car warms up when it's been sitting at a trailhead for 8 hours at 5 degrees F! It does take a while for the regen to become effective though.

evsisson | January 6, 2016

The climate control is at the bottom of the touch screen - always showing. The button at the bottom center turns the climate control off and on. The button just above it, which says "CUSTOM", gives you a screen for changing settings.

A minor problem: when you open the CUSTOM screen, the climate control turns on, and you have to hit the climate control button if you want it off.

Climate control shuts off when you leave the car.

sbeggs | July 19, 2018

Bumping faves