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70D AC Problem

The auto temperature control doesn't work. It can be 100 degrees in the car and the temperature is set to 64 degrees and the fan runs at about a 25% level.
I have to move the temperature control to LO to get the fan speed to pick up to about 100%. In effect all I have is a manual AC control system because I have to continually adjust the temperature. It's like I've gone back in time 20 years.
I needed to take the car in to get my nosecone replaced (was scratched at delivery) and asked them to fix this. The loaner I was given operated like all other cars I've had for the last 20 years, the fan ran at max speed until the cabin cooled down.

This was the service center's response: Checked A/C operation and performance. Found everything working as designed. Auto
feature takes many inputs into account, when determining fan speeds and vent positions.
It may take a while to reach desired temperature during extremely hot weather, especially
when battery cooling is required.

I think they just didn't have any idea how to fix it.
 
The auto temperature control doesn't work. It can be 100 degrees in the car and the temperature is set to 64 degrees and the fan runs at about a 25% level.
I have to move the temperature control to LO to get the fan speed to pick up to about 100%. In effect all I have is a manual AC control system because I have to continually adjust the temperature. It's like I've gone back in time 20 years.
I needed to take the car in to get my nosecone replaced (was scratched at delivery) and asked them to fix this. The loaner I was given operated like all other cars I've had for the last 20 years, the fan ran at max speed until the cabin cooled down.

This was the service center's response: Checked A/C operation and performance. Found everything working as designed. Auto
feature takes many inputs into account, when determining fan speeds and vent positions.
It may take a while to reach desired temperature during extremely hot weather, especially
when battery cooling is required.

I think they just didn't have any idea how to fix it.
What fan speed does your system show when you believe this is happening? Tap the A/C control button to fly up the panel and look at the fan speed. My experience tells me you might be seeing normal behavior. I would expect it to read '7' when it's set to 65 or 66. It tends to shift to 8 or higher only when set to LO.
Also make sure you are set to full auto, not custom auto.
 
My experience tells me you might be seeing normal behavior. I would expect it to read '7' when it's set to 65 or 66. It tends to shift to 8 or higher only when set to LO.

This doesn't sound normal to me. The fan speed should be dictated by the difference in cabin temperature and the temperature you have set. When there is a 36 degree delta then the fan speed should not be "7" just because it's set to 65 or 66.
It should be max.
 

jerry33

(S85-3/2/13 traded in) X LR: F2611##-3/27/20
Supporting Member
Mar 8, 2012
20,439
27,182
Texas
My A/C must be different than everyone else's because it hardly ever runs more than two fan blades on the screen and the temperature is fine with no additional window tinting (I do have the sunscreens, but they are 95% for light control.) I don't really know what two fan blades equates to in the manual setting as I've only looked at the manual setting screen a couple of times in 2.5 years. (Range mode always off in summer.)
 

AmpedRealtor

Well-Known Member
Jun 30, 2013
6,433
4,164
Phoenix, AZ
This doesn't sound normal to me. The fan speed should be dictated by the difference in cabin temperature and the temperature you have set. When there is a 36 degree delta then the fan speed should not be "7" just because it's set to 65 or 66.
It should be max.

Greg, unfortunately this is the current state of the HVAC software. It is what it is. There is no "fix" for the behavior you describe until Tesla' fixes the software. This is how all Model S cars work because they all use the same software. Until Tesla fixes the software, find a workaround.
 
Greg, unfortunately this is the current state of the HVAC software. It is what it is. There is no "fix" for the behavior you describe until Tesla' fixes the software. This is how all Model S cars work because they all use the same software. Until Tesla fixes the software, find a workaround.

Then why did the loaner Tesla I drove operate the way it is supposed to?
 
Then why did the loaner Tesla I drove operate the way it is supposed to?


There are a lot of possibilities. I'm a long way from understanding the logic of the HVAC system but I'm beginning to be able to use it more effectively.

Like you (and others) I came from other cars where the system, left on "auto," just worked. I never touched the AC controls for months at a time. The Tesla system is not nearly that well sorted out, but I'm learning that it is capable of cooling the car adequately under most conditions.

Two things to check right away: make sure that you aren't in "range" mode, and make sure you haven't touched the fan controls. If you adjust the fan to increase its speed, you lose the auto function until you specifically set it back to auto.

The temperature delta seems to be ignored in my car if the temp is set to 71 or higher. It can be 115 in the car (and 98 outside), set to 71, and the fan goes no higher than 6 or 7. If I lower the temp to 66, the fan goes to 11 almost immediately. I generally start with the temp set to 66 or LO, and gradually work it up if needed. This gets the AC to do what I want

I know this defeats the purpose of having an automatic HVAC, but I believe the hardware is capable and eventually the software will catch up. Right now it seems the available software expertise in the company is being used for higher priority items like getting the autopilot ready for release and improving the trip planner.

Also, if you can predict when you will get in the car using the phone app to precool the car is a huge help.
 

CHG-ON

Still in love after all these miles
I find that I have to fiddle with mine all the time. But I always seem to have that issue with auto systems. What I do is leave it in recirc manually, have everything else set to auto and adjust the temp to get to the end fan speed that I want. Seems to be the most convenient work around for me, though not optimal. I also drop all windows for the first few minutes of the drive. I've always done that to evacuate as much hot air as I can. I got the sunscreens for the pano and rear and they do seem to make a difference in heat gain. I live on the CA coast, so it never gets very hot here, but the car can easily get way up there when sitting in the sun.

The reason I leave it in recirc is more to avoid pulling the fumes of stinky gas an especially diesel vehicles.
 

vdiv

Chief Grump
Jan 20, 2015
674
841
Reston, VA
Mine is temperamental as well. Sometimes it cools really rapidly (the blower spinning fast cold, air freezing my face off) and sometimes it hasn't had its morning coffee. I was told that the car can redirect cooling for the battery/power electronics but I have no indication they need it nor that is happening. Wonder if the system takes into account the outside temperature and the incoming solar radiation.

Another thing that I found is the hysteresis between cooling and heating is really narrow. It can be barely below the set temperature (in the morning) and it will run the heater.
 

SomeJoe7777

Marginally-Known Member
Mar 28, 2015
2,271
6,077
Houston, TX
As others have said, the software is not yet up to par.

The most convenient work-around I've found is to put all controls in auto except for the air source (I manually set that to recirc), and then control temperature. You can program the right scroll wheel on the steering wheel to set the climate control temperature, and I use this to control the amount of cooling I want. When it's really hot outside, I just roll that down to LO (this puts fan at 11 and cooling on max), and then scroll it up from there when the cabin cools off.
 

Ingineer

Electrical Engineer
Aug 8, 2012
1,507
3,716
I have this gripe as well. I'd like to add one as well; You can't turn off the heater! The PTC heater draws a lot more than the A/C compressor for heating vs. cooling the same delta, yet I can manually select whether the A/C runs but the heater has no such bypass. In an ICE heat is free, but in an EV heat is extremely "expensive" battery-wise.

What they should have done is add in the $18 reversing valve and turn the A/C system into a heat pump with about 3X the efficiency.

So Tesla, if you are listening:

1. FIX the automatic system, it's hardly automatic! As everyone above notes, you have to constantly fiddle with it to be comfortable. Need inspiration? Check out a 1982 Cadillac Eldorado. The Delco automatic system in that car really worked well. The system in my LEAF can even hold a temp a lot better!
2. Add in the reversing valve and electronic expansion valve to make the system a heat-pump. Look at a 2013 Nissan LEAF if you want to see how to implement such a system.
3. Allow manual disabling of the PTC heater just like the A/C compressor can be now. (Except for battery/electronics use) This is especially important if you don't implement #2. As noted above, we have to constantly diddle the temp setting to be comfortable, and I've seen the system jump to heat mode too quick when you raise the temp a few degrees, especially when the left/right settings are not sync'd. This probably wouldn't be a big issue if the auto logic worked properly.
 

mknox

Well-Known Member
Aug 7, 2012
10,103
1,894
Toronto, ON
I guess I'm not the only one!

My two complaints are:

The temperature setting does not seem "accurate". I keep mine at 67F and it makes the car feel about how 72F did in all my previous cars with Auto HVAC

The fan is usually running too slowly. I keep "Fan Speed" as the default on my right steering wheel scroll wheel and just thumb it up when I need to. A press of the scroll wheel puts it back in "Auto".
 

JPP

Active Member
Feb 4, 2013
3,082
1,342
SF Bay Area, CA
My two complaints are:

The temperature setting does not seem "accurate". I keep mine at 67F and it makes the car feel about how 72F did in all my previous cars with Auto HVAC

The fan is usually running too slowly. I keep "Fan Speed" as the default on my right steering wheel scroll wheel and just thumb it up when I need to. A press of the scroll wheel puts it back in "Auto".

I concur--the default right scroll wheel on both of our S is Fan Speed...leave the temperature settings and everything else on Auto, and adjust the fan as needed. Not just a 70D issue....
 
Strange... I do agree that the temperature itself is off - but every single car I've owned has had a different "offset" for what I think is comfortable. Some cars I set to 73F, some I set to 67F. But every one of those cars has been able to keep that temperature without too much trouble... my Telsa definitely keeps the temperature within a band tightly enough that I virtually never touch the settings. I just set whatever temp it is (i think the tesla is 69F?) and turn everything to "auto" and let it do it's thermostatic thing.

I do have the car tinted (incl. the windshield) and that makes the A/C do a lot less work in the summer... but even when it's really really hot the A/C cranks up to full pretty quickly and then ramps back down as it cools.
 

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