HVAC settings, when and how?

[alexander3192]

Hi folks, I have to post this even if is a little embarasing, but I never owned a car with air condition before and I don't understand how HVAC works in Model 3.
I am a new owner and I have read the manual for the last couple of months, but the climate control is still overwhelming for me. Although I understand the user interface and what buttons are/do, I do not understand how the actual system works.

I know this is probably a lot to ask, but I would really appreciate if someone can spare some time to explain it to me. The explanations in the manual are vague, often explaining what the buttons do, but not really in which situation or how should it be used. For example Auto says that activates auto mode, but what exactly that means I don't know.

1. I usually just press the Auto button and set the temperature to 17C, but I noticed that on this mode the fans never stops. As I understand, the auto mode should not stop the fans when the cabin reaches the desired temperature? Same with turning them on again if the temperature drops. Instead the fans are constantly blowing in my face which is quite unpleasant.

2. What exactly is A/C button and when should I use it? From what I know is the air condition and that should be activated only when I want to cool down the cabin, presumbly in winter. However, I noticed that the Auto mode also activates the A/C when I set it for 17C.

3. The fan speed section seems to have a fan speed option when A/C is off and three settings(low med high) when A/C is on. What exactly does that mean and why is different?

4. I never used the recirculation button. When should that be activated or disabled?

Thank you in advance, I hope you can answer to me and I appologize for grammar errors.

 

[alexander3192]

Point number 2, correction.

"From what I know is the air condition and that should be activated only when I want to cool down the cabin, presumbly in summer.

 

[Watts_Up]

Point number 2, correction.

"From what I know is the air condition and that should be activated only when I want to cool down the cabin, presumbly in summer.

In fact, I believe that for any car having air conditioning, when you activate the windshield defroster,
the air first pass through the air conditioner to remove the humidity,
then get heated if you have adjusted the temperature to do so,
and then the air get blow toward the windshield to remove the condensation.
So yes, even in winter, the air conditioning might get activated.

Note: In general, I just set the air conditioning to 'Auto', and adjust the fan speed
to high to quickly remove the fog, and then I lower the fan speed because of the noise.

For heating, I don't like too much having air in my face, so I principally use the seat heaters, especially when I am parked at a Supercharger in winter.
The recirculation improves the air conditioning efficiency by mixing about 50% of indoor and outdoor air together.
There is also a special tab to control the rear fan and rear seats heating.

 

[RTPEV]

The auto setting basically just maintains the set temperature. So if you have it set to 17C it will heat or cool as necessary to maintain 17C. It also directs the heating/cooling air to the appropriate part of the cabin (the floor if it's calling for heat, or the head/face area if it's calling for cool).

I don't think you are correct about the fan coming to a complete stop when the set temperature is reached (#1). You probably want some kind of air flow in the cabin (otherwise it would get stuffy) even when it's at the set temperature. So the fan does continue to run. And this answers your #3 question: when not in AUTO mode (you said A/C, but it's really AUTO mode), you can set the fan speed to LO, MED or HI indicating the amount of air flow you prefer when the system is at the set temperature. There is not an OFF setting, so there will always be at least some airflow, but it sounds like you would prefer as low as possible, so select LO. You should also use the airflow vent direction setting to adjust the airflow to blow above or below your face if that is uncomfortable (I don't know how to describe this setting...basically you just drag the wavy animated air on the picture up, down, left or right until you find a preferred air flow direction).

That covers #1 and #3 I think.

#2: The A/C button engages the air conditioning system. If it's not on, you will just get airflow (or heat if your set temperature is high enough, at least in older models without heat pumps). You pretty much just want this on all the time and let the AUTO mode handle when to turn it on and off. But if you feel you need to disable it for some reason, you can do so with this button. Not everyone agrees with me, but I think AUTO mode quite well, so I just set it and forget it. About the only exception is during the change of seasons when for example it's cold for the morning drive and hot for the afternoon drive. I find at that time of the year I would prefer just vent air, no heating or cooling, so the only way for me to do this is to set the temperature very low (to disable heating) and turn off the A/C button (to disable the air conditioning).

Note that when you use the front defogger, that requires A/C to work, so it would need to be on for that (it may do this automatically, I'm not sure).

Don't worry about whether the button is lit in the winter. It just means that if the car needs it, it will be available. It doesn't necessarily mean it's actually running.

#4: Recirculation. Normally the car takes outside air and vents it into the cabin. This is normally what you want. Recirculation tells the car to not take in any outside air, but rather just recirculate the air in the cabin. There are only two cases I can think of where you would want this: when traveling through a smoky or polluted area and you don't want to breathe the outside air; and when you get into a hot cabin on a hot day, by recirculating the air will cool off quicker--I suspect the car does this automatically though, so I don't every worry about doing that. It cools off quickly enough. So this button very rarely gets used. If you do use it, however, it will get stuffy in the cabin after awhile as the water vapor from our exhalation makes it very humid. Your windows may fog up as well.

 

[alexander3192]

Thanks for your reply. This was very informative and it really answered to a lot of my questions. Now I have a better understanding.
I did some tests and noticed that Auto mode is kinda dinamic.

At first I noticed that I cannot activate A/C or change the ventilation setting (was blasting air to the windshield, face and feet) while on auto.

However I noticed that at some point A/C got automatically activated, same with defog and the ventilators stoped working from face and feet, only from windshield. That makes me think that Auto mod actually can activate/deactivate A/C and defog, as well as fan positions. Is that true? If so that is great and it means that Auto mode would be the best to use at least until I get a better hang of it as it's controlling also AC.

And now one last question. This morning we had -2C outside and the cabin was sitting at 0C and car slighty frozen. I set from the app to defrost and bring the cabin to 20C exactly 10 minutes before leaving. When I got to the car, it was nice temperature, almost 20 and the ice was gone from windshield. However I noticed the battery percentage plumeted from 59% to 54%. Car was not plugge in.

Is it normal to use 5% energy to warm the car up to 20C in 10 minutes? The car is new model LR I find that slighty high, is there any other way people use to warm the cabin that eats less energy?

Thanks again for the answers, I really appreciate it.

 

[Sorny]

Thanks for your reply. This was very informative and it really answered to a lot of my questions. Now I have a better understanding.
I did some tests and noticed that Auto mode is kinda dinamic.

At first I noticed that I cannot activate A/C or change the ventilation setting (was blasting air to the windshield, face and feet) while on auto.

However I noticed that at some point A/C got automatically activated, same with defog and the ventilators stoped working from face and feet, only from windshield. That makes me think that Auto mod actually can activate/deactivate A/C and defog, as well as fan positions. Is that true? If so that is great and it means that Auto mode would be the best to use at least until I get a better hang of it as it's controlling also AC.

And now one last question. This morning we had -2C outside and the cabin was sitting at 0C and car slighty frozen. I set from the app to defrost and bring the cabin to 20C exactly 10 minutes before leaving. When I got to the car, it was nice temperature, almost 20 and the ice was gone from windshield. However I noticed the battery percentage plumeted from 59% to 54%. Car was not plugge in.

Is it normal to use 5% energy to warm the car up to 20C in 10 minutes? The car is new model LR I find that slighty high, is there any other way people use to warm the cabin that eats less energy?

Thanks again for the answers, I really appreciate it.

Defrost puts it into max heat mode; max heat mode will deplete the battery quickly as it sets the temp to "high" and runs the front motor to generate heat. If the windows aren't iced over, just using "climate on" with a set temp will warm the cabin without using as much power.

Also, cold temps will show less battery than warm temps.

I pretty much only ever use "defrost" if the car is iced up. Otherwise, just turn climate on to the normal setpoint and it warms the cabin, seat, and steering wheel sufficiently in about 5 minutes.

If the car isn't buried in snow, with a layer of ice, you probably won't need to ever use defrost mode. And almost certainly never for 20 minutes. Just turn climate on at your desired temp, and within 5-10 minutes, the cabin will be at the desired temp. Even when it's -35...

Furthermore, the car likes to be plugged in. Then, set scheduled departure, and the car will charge to the set limit, and have the cabin at the desired temp by the time you specify. It'll also have the battery warmed up, so you get as much regen and range as the charge limit and temp allow.

 

[Olmo]

Good morning, in any case there is a problem that it would be nice to ask Tesla to modify: in Volkswagens the air conditioning remains on Auto even if the air conditioning is turned off; instead in Teslas, when we turn off the air conditioning, the climate control switches to Manual mode; this is very problematic especially in the medium seasons, because in winter the heat flow is so high that you don't notice it, but when it's a spring temperature outside, the freezing flow of the air conditioning is very annoying

 

[Benito1283]

A/C isn’t only for cooling. It’s for drying aka conditioning the air. If the cabin air is above a certain moisture point, it will run the A/C, even when heating.

 

[alexander3192]

I have noticed that the car somehow intermitently blows hot and cold air on AUTO mode.

I set the temperature to 18celsius and notice that sometimes it blows cold air on my feet. I must investigate further because I don’t think it should blow cold air since the cabin temperature does not reach 18degrees.

It might be a fault somewhere.

 

[jjrandorin]

I have noticed that the car somehow intermitently blows hot and cold air on AUTO mode.

I set the temperature to 18celsius and notice that sometimes it blows cold air on my feet. I must investigate further because I don’t think it should blow cold air since the cabin temperature does not reach 18degrees.

It might be a fault somewhere.

its not a fault. Reference what @Benito1283 mentioned, right above your last post:

A/C isn’t only for cooling. It’s for drying aka conditioning the air. If the cabin air is above a certain moisture point, it will run the A/C, even when heating.

 

[crawfy p]

I have noticed that the car somehow intermitently blows hot and cold air on AUTO mode.

I set the temperature to 18celsius and notice that sometimes it blows cold air on my feet. I must investigate further because I don’t think it should blow cold air since the cabin temperature does not reach 18degrees.

It might be a fault somewhere.

Obviously there will be different opinions on the optimum temperature, some like it cold, some like it warmer. For me personally, 18 degrees Centigrade would make my car feel much colder than I’m comfortable with. I’ve had dozens of cars with climate control and they have always felt most comfortable at 20 to 21 degrees, I think most manufacturers expect users to be around that mark for comfort (anecdotal). In any car I’ve owned, 18 would be too cold for me.