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Air Conditioner Strong While Parked, Weak While Driving?

So I took delivery of my Model S this morning. While
sitting in the car with the delivery specialist, the
air conditioner seemed to be working great, nice and
cool in the car. Once we were done, I left to drive
home.

On the drive home, I noticed it kept getting hot in the
car, and I hadn't changed any AC settings. I kept on
having to crank it down to LO and full blast to get it
cooled down again. It definitely was not holding the
temp at the chilly 69 I had it set to.

Once I arrived home, I was sitting in the car messing
with the touch screen. I eventually noticed that AC
was suddenly strong again and keeping the cabin very
chilly. It felt like it usually does at 69 degrees in
my cars.

So it seems like the AC kind of sucks while driving. I
checked to make sure Range Mode wasn't on, and thus
limiting the capabilities of the AC. It was set to off.

I had the AC on Auto, set to 69, cooling face and feet,
recirculating air. These settings combined in all my
other cars keeps the AC going nicely and it holds a
constant temp in the car, to whatever I've set it to.

So what gives?

Is the AC only really good while sitting still? If so,
that's disappointing because that's usually when it's
needed the least...

Am I just missing something?

Me too. Production date June 26.

@shamrockceo - great question. I've noticed something similar, but don't know if it is a 'real' effect or not. Maybe a combination of factors combined with a perception issue.

Have you tried changing the setting to recirc when driving to see if that makes a different?

Hmm...sounds like that is a bug. You should hit up your local service center.
I've had no problems with the A/C.
In fact, I've realized that when I use the iPhone app to pre-cool the car, that I only need to engage it a few minutes before going out to the car, otherwise it is too cold!

The AC settings were set the same during initial walkthrough with the delivery specialist, driving home, and sitting in the car at home. I never changed the settings once I set them initially.

I don't believe it's just in my head, or a perception issue. The AC very apparently does not work very well at all while driving the car. It only works very well while the car is not moving.

This is pretty devastating, for me personally, if there's no fix for this. I know for a fact that I will NOT be happy at all with a $100,000 car that can't even keep the AC cold while driving the car.

It would be fine if all I did was sit in my car all day and didn't have to drive anywhere. But alas, the car is moving 99.99% of the time when I'm in it - which means the AC will be blowing lukewarm air 99.99% of the time, unless I'm constantly manually cranking it down to LO with vents full blast.

The car is cool. The AC definitely is not.

@NKYTA - Yeah, the AC is great if the car is sitting still. It's only while it's moving that the AC performs miserably. I guess I'll wait for more responses to see if this is a fluke or common.

@shamrockceo
Stop by your local service center and get a tech to take a ride with you.
This sounds abnormal from my experience in the last 7 months.
Tesla will make it right if it is wrong.

I agree with the other posts. I live in Miami, FL and it is scorching right now and I haven't had an issue. I do have tinted windows, though, which helps but overall I've been very comfortable.

Are you driving your car in extended range mode or whatever that's called? If so, the A/C performance is reduced while in that mode in order to maximize your range. Try turning that off.

@NKYTA - Alright, I'll try that. Wish I would've known about the issue before I drove 30 miles home, haha. But oh well.

@AmpedRealtor - Yes, I checked to make sure Range Mode was turned off. It was, so that's not it.

@garcilamd - I'm in Houston, TX so very hot here also. I'll be getting the windows tinted, so if service can't fix it, hopefully that will help a lot.

If it's really hot where you are, is it possible that some of the A/C is being diverted to keep the battery within its upper temp limit when the car is being driven?

I experienced the same type of symptoms but have the main button now resolved them. This is my take. There are two funny things with the ac, 1 i believe is a bug, the other intentional. First the bug: if you put the entire ac system on auto from the top button, it works fine. Keeps the cabin at the set temperature (except as noted below). If you set any option after that, like fan, recycle air or vents, it no longer is on auto and you have to manually manage the ac. I just leave it on auto unless i want to cool my feet, but when my toes are cold, i reset the ac using the main auto button.

2nd, the ac uses some sort of funky algorithm that takes into account the outside temp, so if it is less than about 80 degrees outside. It will turn the compressor off to save energy. So if it's 75 and sunny, the cabin will be toasty.

Pls ignore the first main button...tablet...

We're in Phoenix, don't have tinted windows, and our AC works really well. We do sometimes have to lower the temp several degrees to keep the back seat passengers comfortable. We've had our MS for about 7 months (and even ran the AC a bit in winter). Ours works well even when it's 118 out; I'd have service check your AC.

+1 @ David Trushin

We do almost always keep the system on full auto.

We also live in AZ and our A/C has been fine since we have had our MS (6/8 delivery) but think it does tend to 'slow down' more than we were used to in our previous car. That being said and not sure if there was any tweaks, since we moved to v.61 it seems to be not quite as 'weak' and can feel it a bit more when driving without having changed the temp.

No problems with mine

Mine works fine, but I leave it on auto and just adjust temp up and down if I feel I need more/less. For me, the range is 67 to 69 usually. 67 during hot sunny days, 69 during a cool night.

I don't know if this is the case with yours, but if you have the soft plastic screen protector on your touchscreen still, that could interfere with your AC. I had a loaner and the first two days the AC was blowing inconsistently, and the car was turning on by itself. We eventually figured out it was the soft screen protector that was causing it. The second hard screen protector stayed on the screen without causing any interference.

If you still have the soft protector on, try taking that off and see if it helps.
Otherwise I hope Tesla gets your car fixed.

I've noticed that I sometimes feel warm when the temperature is set, say, to 68, and weather is sunny and not all that hot outside. The reason seems to be that the fan speed goes quite low when in auto mode, if the cooling doesn't have to work hard.

Sometimes I just lower the temperature setting a notch or two, but that might actually be uncomfortable. The other option, which works well for me, is to override the fan speed. Typically, when I feel warm it's because the auto mode fan has dropped to 4 or 5 or so, which isn't enough when the sun is beating down on me. I just raise the speed to 7 or so and comfort returns.

This seems like an area that will need further tuning.

I don't like the auto mode for the AC fan as it is often too aggressive if the car is warm. Rather, we use the right scroll to control the fan speed manually.

Update: So I took my car into the service center here in Houston. (Side note: the staff there is really friendly and accommodating, I was impressed).

And I'm a bit happier because I had driven home and AC sucked, then I charged the car for a while and drove back to the service center after a few hours of being home. On the drive back to the service center, the AC seemed to work a lot better. I had everything set to auto except the fan speed, which I set all the way to maxed at 11, haha. Still not what I'm used to with previous cars, but maybe there's room for improvement in the AC system with Tesla.

What it seems to boil down to is that there isn't a problem with the AC that they could find after running diagnostics, etc. Seems weird, but I wonder if the initial terrible AC experience had some user error built into the situation. Oh well.

I'm going to get the windows tinted as dark as legally possible, and get an anti-heat tint installed on the pano roof. I'm hoping that will make the efforts of the AC's cooling last longer, thus not needing to run the AC at full blast constantly to maintain a comfortable temperature.

Thanks for the replies and thoughts everyone, appreciate it.

The screen protector is 2-layered during shipping for protection. The top layer is unnecessary, and insulates the sensor for the screen.

@shs - the fan speed is too aggressive? That's the first time I've heard that. I'm in Florida and have to set the temperature down to 68 to get the fan speed to increase significantly.

@Nick - I'm with you. There is no such thing as too aggressive with the fan speed.

This thread needs OS versions so we don't get confused!

Use your phone app. (but not while driving!) to compare the interior cabin temperature between what is reported by the app. and what is reported by a real thermometer located near the USB ports (but out of the sun). That may give you a clue as to what is happening. Note that the phone app. won't always report the cabin temperature unless you turn on the A/C (or heater).

In my own car without pano sunroof, VIN 028xx, I leave everything on AUTO and normally only have to move the temp between 71° and 73° F. to be comfortable. Yes it blasts with the fan on 11 for about 1 or 2 minutes if the car has been sitting in the sun, but then it settles down nicely and holds the temperature pretty well.

But in my brand new loaner P85, VIN 145xx, with PANO roof, using the same settings, I noticed problems similar to what @shamrockceo described.

In the newer Model S, Tesla seems to have moved the location of the cabin temperature sensor. It's now located above the USB and 12V ports, with a large set of small holes visible that are not present on my much older Model S (in which the temperature sensor is located behind the 17" display, I believe). The original location was a warm spot, so the software always thought that the cabin was much warmer than it actually was, and AUTO made the car way too cold. You had to set the thermostat to 75° or 76° to be comfortable. They fixed that issue a few months ago (in 4.4?). I think all they did was subtract a few degrees from the reported temperature to compensate for the extra warm readings.

However, now that the temperature sensor is in a new spot (in newer cars), I wonder if the firmware knows that it now has to account for two different sensor locations or styles? If not, it could account for the odd behavior, especially if the heat from the sun beats down on the pano roof, warming the center console quite a bit.

@Bob W - I think you're on to something here. I wasn't aware of the thermostat location being moved in newer cars, so definitely makes sense if they did indeed adjust the thermostat a few degrees to compensate for the old location.

I really wish this would get fixed somehow for newer cars, if all that is true.

Though I think a big problem in itself is the pano roof itself. Even with the cabin cool with the AC being cold and full blast, there's still a significant amount of heat coming in from the pano roof. My body feels cool with the AC on full blast, but my head is noticeably hot, and putting my hands right next to the windows and pano roof glass, you can definitely feel the heat just resonating into the cabin.

Hoping that getting the windows tinted dark and limo tinting the pano roof with an addition heat shield of some sort (probably also on the back window) will significantly help to reduce the heat issues.

As to fan speed, I have found that when the AC is first on, it uses a fan speed that is higher than I might like in term of noise. I generally dial it back to 8 or so Anything higher than that I find annoying. It really seems to blast and I am not sure that a blast of warmer air actually provides more cooling than a lower, but colder airflow. On the other hand, one the car cools down a bit, the the fan speed sometimes drops below what seems to me to be the optimum level - hence I tend to use manual control. Most experience is with 4.5. Just got .61 today but haven't tested the auto fan speed mode.

Yeah, for the record, I'm on v4.5 (1.33.59). I wish there was a "Check for Updates" button I could press to update on demand, rather than waiting until, by random stroke of luck, my car decides to update itself.

@shs Yeah, that's what I have found myself doing too. Set the temp to 66 or so, then manually control the fan speed. I want to be about 72F, but prefer having 66F at speed 1 or 2 instead of 72F at speed 6.


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