Does Cabin Overheat “No A/C” mode work for anyone?

[dafish]

EVRider:

Can we assume "Fan Only" is by default fresh air? Be pretty useless in recirc....

 

[stopcrazypp]

I was wondering this as well. Looking around I don't find a definitive answer, but most believe the car does sleep as long as the temperature stays below the set temperature for COP.

The idea is that the temperature sensor is "passive" and once it goes over X° car turns on and cools the cabin.

In practice the car doesn't sleep well since in sunny areas the COP has to turn on intermittently a few times per hour, so the car can never sleep for longer than say 15 minutes tops.

Since finding this out I did turn it off and I go for the "turn on climate control 30 minutes before I want to leave somewhere". COP is only for comfort on short stops. When I'm at work for 8-10 hours the COP wastes energy keeping the car cool. (The moment your car is very hot it radiates heat as fast as it absorbs it, so you get "free" COP. There is little point in not wanting the car get hot during the hours you are not using the car).

What I also checked for: a hot car cabin does not damage the computer/screen. The manual states this specifically. COP is for comfort of the passengers/driver, not to prevent damage to the vehicle. Some people worry about this but that is not proven to be correct.

I don't believe monitoring keeps the car alive. I've seen my car sleep by small segments in high, but not very high temperatures (using TeslaFi).

From logs people posted, I think the system sleeps and wakes up every 15 minutes or so to check the temp. That coincides with the 15 minutes the manual mentioned it might take to activate. "Cabin Overheat Protection may take up to 15 minutes to enable once you exit the vehicle."

Model 3 Owner's Manual | Tesla

Learn how to operate and customize the interior climate.

www.tesla.com

One way to check is to activate it in cold weather and see how often the car wakes up compared to with it disabled.

I don't think the car necessarily has a way for the temp sensor to wake the car up based on detected temp.

 

[EVRider-FL]

EVRider:

Can we assume "Fan Only" is by default fresh air? Be pretty useless in recirc....

I would assume so, but I never use the Fan Only setting because it wouldn't accomplish much here in south FL. I don't let the car run down the battery enough to worry about not using the A/C.

 

[GtiMart]

Cop is on all the time in my car, even in winter. I do not see it wake up at all while I'm at work when it's cold. It seems to wake up when it needs to only. I use teslafi to check that.

 

[LadyOnikara]

I was looking at the refresh Model S manual and it’s not documented there, but I do see the No A/C setting in the Model 3 manual. Just checked the mobile app, and I see that option for my 3, but not for my S. For the S, it looks like this:

View attachment 950930

Um, what's the "Bioweapon Defense Mode" thing? Do they only have that in the Tesla App in Area 51 or something? Or for something other than Model 3? I don't have that on the settings for Casper on my app.

 

[EVRider-FL]

Um, what's the "Bioweapon Defense Mode" thing? Do they only have that in the Tesla App in Area 51 or something? Or for something other than Model 3? I don't have that on the settings for Casper on my app.

It might only be available on the S, X, and Y. Our 2018 Model 3 doesn't have it.

From the manual:

"If your Model S is equipped with the medical-grade HEPA (High Efficiency Particulate Air) filter, this filter ensures the best quality air inside the cabin whenever the climate control system is on and outside air is entering the cabin (recirculate is off). The HEPA filter is extremely effective at removing particles, including pollution, allergens, bacteria, pollen, mold spores, and viruses. Both the HEPA filter and the secondary filtration system also contain activated carbon to remove a broad spectrum of odors and gases. When you engage Bioweapon Defense Mode, the positive pressure inside the cabin minimizes the amount of outside air that can enter the vehicle."

 

[LadyOnikara]

It might only be available on the S, X, and Y. Our 2018 Model 3 doesn't have it.

From the manual:

"If your Model S is equipped with the medical-grade HEPA (High Efficiency Particulate Air) filter, this filter ensures the best quality air inside the cabin whenever the climate control system is on and outside air is entering the cabin (recirculate is off). The HEPA filter is extremely effective at removing particles, including pollution, allergens, bacteria, pollen, mold spores, and viruses. Both the HEPA filter and the secondary filtration system also contain activated carbon to remove a broad spectrum of odors and gases. When you engage Bioweapon Defense Mode, the positive pressure inside the cabin minimizes the amount of outside air that can enter the vehicle."

Ah, okay! Interesting name for a mode. Wow!

 

[Chewy13]

I’m not sure it does much.
I’ve got a sunshade for my roof, and the sunshade for my front windshield.
The front windows are a Llumar Formula 1 Stratos 40% ceramic tint, and the rears/rear windshield is an 80% Llumar Air ceramic tint.
Didn’t do much in the 93 degree Massachusetts sun with the windows cracked all day.
Got so hot my rear dashcam adhesive let go and my camera was dangling.
Yes, 142 degrees. Needless to say, I opened the trunk and rolled all the windows down immediately.

 

[Abraham]

I’m not sure it does much.
I’ve got a sunshade for my roof, and the sunshade for my front windshield.
The front windows are a Llumar Formula 1 Stratos 40% ceramic tint, and the rears/rear windshield is an 80% Llumar Air ceramic tint.
Didn’t do much in the 93 degree Massachusetts sun with the windows cracked all day.
Got so hot my rear dashcam adhesive let go and my camera was dangling.
Yes, 142 degrees. Needless to say, I opened the trunk and rolled all the windows down immediately.

Interesting, yeah that’s not ideal. And you’re also reactivating it every 12 hours? I do it by turning climate on for a few seconds every morning.

 

[Miata Head]

I don't get any notifications for either, and I park in my driveway in the hot SoCal sun. I set on 'no a/c', can't see a reason to kill energy with a/c on just sitting there. if something in the car 'deteriorates' while just sitting there in the sun, they need to go back to the drawing board with that. what car doesn't sit in the sun?

 

[dafish]

I’m not sure it does much.
I’ve got a sunshade for my roof, and the sunshade for my front windshield.
The front windows are a Llumar Formula 1 Stratos 40% ceramic tint, and the rears/rear windshield is an 80% Llumar Air ceramic tint.
Didn’t do much in the 93 degree Massachusetts sun with the windows cracked all day.
Got so hot my rear dashcam adhesive let go and my camera was dangling.
Yes, 142 degrees. Needless to say, I opened the trunk and rolled all the windows down immediately.

I don’t know yes or no on the cabin air, but that don’t sound like a glowing testament to Llumar performance.

 

[Chewy13]

I don’t know yes or no on the cabin air, but that don’t sound like a glowing testament to Llumar performance.

I don't have the roof done (which is very expensive to do on the MY) - and the roof sunshade is just this weird metallic dot-matrix, which I doubt does anything for heat rejection.
I picked up a $60 Visible Light/UV/IR meter on AliExpress and the rejection is spot on according to the cutsheets - and in direct sunlight while driving, you can feel how much it cuts down - versus through the windshield or a rolled down window.
I'm tempted to do the front windshield in AIR 90 - I just don't want to deal with the annual state inspection.. Also FWIW - my car is blue, not white. But if the roof is the true culprit for heat when parked, then I'm not sure I'm going to bother with the windshield - since I just put the sunshade up anyways.

 

[dafish]

Testing shown on the roof of MY posted on YouTube suggests the factory tint pretty effective. Mind you I have absolutely no expertise in this area.

 

[stopcrazypp]

I’m not sure it does much.
I’ve got a sunshade for my roof, and the sunshade for my front windshield.
The front windows are a Llumar Formula 1 Stratos 40% ceramic tint, and the rears/rear windshield is an 80% Llumar Air ceramic tint.
Didn’t do much in the 93 degree Massachusetts sun with the windows cracked all day.
Got so hot my rear dashcam adhesive let go and my camera was dangling.
Yes, 142 degrees. Needless to say, I opened the trunk and rolled all the windows down immediately.

Did your sunshade come with a separate opaque reflective layer? The regular transparent cloth one would be much more limited in heat rejection (although it still helps).

Note both sunshade and tint only provides temporary relief. It helps a lot while driving and for very short stops, but if parked for a while, the heat will still eventually saturate. Basically what they do is slow down the speed at which the car heats up, it does not prevent it from heating up completely, if given enough time in the sun.

 

[Chewy13]

Did your sunshade come with a separate opaque reflective layer? The regular transparent cloth one would be much more limited in heat rejection (although it still helps).

Note both sunshade and tint only provides temporary relief. It helps a lot while driving and for very short stops, but if parked for a while, the heat will still eventually saturate. Basically what they do is slow down the speed at which the car heats up, it does not prevent it from heating up completely, if given enough time in the sun.

Oh agreed - I actually have two different sunshades (one black, one grey-ish/headliner color). The black one has the second metallic layer, which I will try tomorrow. The headliner color variant is just a single non-mesh layer, with this weird metallic dot-matrix printed onto it - which I suspect is just a gimmick.

I was hoping that leaving the windows cracked/vented, and having the No A/C COP would keep the temps at least somewhere close to outside temps - but clearly not the case. I wonder what the temp would get up to with the windows shut, No A/C COP off, and no windshield sunshade...
I forgot a cellphone in the car once, and the heat ruined it - the battery swelled right up.

 

[Miata Head]

I don’t know yes or no on the cabin air, but that don’t sound like a glowing testament to Llumar performance.

Gonna be pretty hard to invent tint that breaks the laws of thermodynamics. After 2 hrs in the sun, no amount of tint will make a significant difference.

 

[Chewy13]

Same test - exact same parking spot actually. Similar forecast, but this time with the black roof sunshade, with the metallic "sheet" sandwiched between the glass and the sunshade/headliner.. will post results later.

 

[Chewy13]

Guess there isn’t much difference in roof sun shades!

 

[alexcue]

As far as my MY, yes it does work. I can tell that it does wake up the car to run and does lower the temperature without having the AC run. Car will sleep again for a while then will turn on again to start cooling. I never get any message from the app that it has run though, but TeslaFi does show what's going on pretty clearly.