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I have been very frustrated by this same problem in my 2021 Model Y. The car can make plenty of cold air, and it can make plenty of hot air, but it has a very difficult time regulating the temperature. One day 68 is barely cool, and the next day 76 is freezing cold! It really seems to me the car is having problems measuring the cabin temperature. I have used multiple thermometers and the temp is all over the place.
temp/humidity sensor in the car going faulty isnt uncommon

one way it manifest itself is for me the car failing to activate Climate Keep, or remotely send climate instructions, most often when car is at extreme temperatures i.e. in extremes of summer or winter.
 
I have owned at least six different cars with automatic climate control. My Model 3 is by far the worst. About once a week I have to turn automatic mode off and back on to get it working.

When it is working, I often have to adjust the temperature setting by 2 or 3 degrees as the outside conditions change.
 
... With an EV equipped with a heat pump there is only heating or cooling available.
This is what I thought at first too, and it makes sense by conventional designs. But then after more research I learned that the Tesla Octovalve system actually can both heat and cool simultaneously, and it does as a matter of normal operation! Believe it or not, there are two separate coils in the air handeler. One evaporator coil for cooling the air, and another condenser coil for heating the same air. Both of these can be active at the same time, so it should be able to perfectly control both temperature and humidity.

The system also both heats and cools the battery in much the same way. It's basically just a hugely complex heat pump moving heat from wherever there is too much of it to wherever there is too little of it. It principal, this seems like it has the potential to be the greatest climate control system on the planet, but in practice it doesn't seem to work too well for the cabin.

I hope they fix it with a SW update or new sensors some day.

More info here:

Screen Shot 2021-10-18 at 9.35.17 AM.png
 
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Great thread. It's interesting to see the responses. Not sure if it's in any owners manual but I remember hearing or seeing somewhere that Tesla recommends keeping the climate control on Auto. I guess I'm old school and have always adjusted the climate with the fan speed. Probably not the best way to do things but it as always worked keeping the temp at Hi or Lo and adjust temperature with fan.
That just might work better than Auto.
 
Tesla should have a sensor to detect the location of the sun and compensate by providing additional cooling to the "hot" side of the car.

Pretty sure my 2015 Impala had one. Tesla might even be able to use the AP cameras to "find" the solar angle and relay that info to the HVAC.
Acura TLX took that to the next level. GPS augmented climate control. That has been since at least about 2010.
 
This is what I thought at first too, and it makes sense by conventional designs. But then after more research I learned that the Tesla Octovalve system actually can both heat and cool simultaneously, and it does as a matter of normal operation! Believe it or not, there are two separate coils in the air handeler. One evaporator coil for cooling the air, and another condenser coil for heating the same air. Both of these can be active at the same time, so it should be able to perfectly control both temperature and humidity.

The system also both heats and cools the battery in much the same way. It's basically just a hugely complex heat pump moving heat from wherever there is too much of it to wherever there is too little of it. It principal, this seems like it has the potential to be the greatest climate control system on the planet, but in practice it doesn't seem to work too well for the cabin.

I hope they fix it with a SW update or new sensors some day.

More info here:

View attachment 722869
Ok, I'll buy it. It sure looks true from the drawing but in practice it seems to do a poor job. Supposedly this 2021.36 software I just got is supposed to regulate cabin temperature better. We'll see.
 
Auto works great for me. Only issue I have is when an especially foul smelling vehicle driving in front of me causes the cabin to reek of the fumes they emit. I wish there was a pm 2.5 sensor to automatically turn recirculation on.
 
Ok, I'll buy it. It sure looks true from the drawing but in practice it seems to do a poor job. Supposedly this 2021.36 software I just got is supposed to regulate cabin temperature better. We'll see.
Exactly. It seems to be a very flexible and sophisticated system and ought to be able to work much better than it is currently. I am hoping a SW fix is possible. I had not heard that 2021.36 had changes related to temp regulation. This is great news. Just got the update notice today.
 
I have noticed an issue with my M3 and and the same with the Nissan Leaf I owned for six months. This seems to be the nature of EVs.

The problem arises when the temps outside are somewhat close to the desired interior temp. With an ICE car there is always warm coolant flowing through the heater core. The system can use a combination of engaging the AC to first cool the incoming air and remove any excess moisture and then pass it over the heater core to warm it up again. By blending those two functions it is able to closely maintain a desired temperature for the outlets and therefore inside the cabin. With an EV equipped with a heat pump there is only heating or cooling available. There is some modulation possible by blending outside air but not much. If the OAT is significantly above of below the desired cabin temp it seems to do a pretty good job. At least in my experience. It is that "null zone" that is difficult to maintain.

As mentioned here the greenhouse effect changes the equation as to perceived temperature. I purchased and installed the roof screens. Easily installed and removed. Most people didn't even notice them. Just thought it was a conventional headliner. Made a big difference. I just took them out this weekend as the temperatures are getting cooler.

As an aside, My 2014 Q50 hybrid had the optional hi-tech HVAC. It had a grapeseed polyphenol air filter with plasma clusters (ionization). After seven years of ownership the cabin had no odor whatsoever. And the cabin temperature control was spot on. After being spoiled with that, it is missed. The so so HVAC in the Tesla and EVs in general is my one and only disappointment. Sounds like a #FirstWorldProblem.
I have noticed this exact thing. If the outside temp was 72F and I have the HVAC set at 72, the car would get hot. It's like that it thinks that putting 72F air from the outside it good enough because the outside air is 72F. Unfortunately, if the sun is out and/or if there are extra people in the car, bringing in 72F air at fan speed 2 or 3 is not going to be enough. Either ramp up the fan speed if the interior temperature is rising or start running the AC at the lower fan speed.

If it was 85 outside and I have it at 72, it would do a fine job.
 
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I think the ICE car manufacturers have many more years of experience in the area of automobile climate control, and they probably have learned things like this over the years.

Tesla may be taking an approach more like one would do for climate control for a house, that is, not considering the subjective "feel" in the car when the sun is shining, or knowing not to use the outside air simply because it is close in temp to the set point, or not to turn on the heat during a time of general cooling (like Summer).

The good news is almost everything in Tesla's system is software controlled, which means it may be possible to improve performance with SW updates.

I think Tesla will get better over time and eventually have one of the best climate controlled cabins ever, but there are going to be some growing pains as they learn. This is why I believe it is important to discuss this in forums like this and to provide feedback to their developers.
 
I have noticed this exact thing. If the outside temp was 72F and I have the HVAC set at 72, the car would get hot. It's like that it thinks that putting 72F air from the outside it good enough because the outside air is 72F. Unfortunately, if the sun is out and/or if there are extra people in the car, bringing in 72F air at fan speed 2 or 3 is not going to be enough. Either ramp up the fan speed if the interior temperature is rising or start running the AC at the lower fan speed.

If it was 85 outside and I have it at 72, it would do a fine job.

Same. I have to adjust the temp regularly during drives since it just seems to blow either very hot or cold relative to the outside temperature, which tends to vary a lot over a short time or distance. It doesn't seem to just maintain the set temperature in a nice consistent way. I also think that I just notice it more when I have to adjust the temperature in this car vs. others because I hate using the screen for it rather than a knob or button.
 
Well I am surprised but happy to report that since upgrading to 2021.36.5 I notice the climate control seems better! It’s only been two days, but I am cautiously optimistic. Time will tell. Feeling hopeful!
After two weeks+ since the update, I too have noticed an improvement. Not perfect but much better. I can live with this. Remember people, this car is a work-in-progress. Getting better all of the time.
 
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Day 3 today. So far so good. One thing I noticed that is different is the system seems to turn on and off passenger dash vents on its own over time. I especially notice this if I manually change the set temperature. I'm pretty sure that previously it would only activate the passenger vents if someone was sitting in the passenger seat, but maybe I am wrong. I don't recall the vents turning on on their own before the update.
 
Using voice control it is sooooo easy to change temperature/fan speed/fan direction etc without ever touching the screen
You must have the right accent in Texas.

If I ask my car to do anything via voice control it totally misunderstands me every time. I feel like the Pontius Pilot character in the Life of Brian. “Phwo him to the floor centuwian” “Oh, yes he did sir”

The British accent is a bit beyond Tesla at the moment. Must be that mix of up-tight, stiff upper lip vocalisation and regional accents. 🙂
 
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You must have the right accent in Texas.

If I ask my car to do anything via voice control it totally misunderstands me every time. I feel like the Pontius Pilot character in the Life of Brian. “Phwo him to the floor centuwian” “Oh, yes he did sir”

The British accent is a bit beyond Tesla at the moment. Must be that mix of up-tight, stiff upper lip vocalisation and regional accents. 🙂
Going to have to push back on that...I'm a Brit living in Texas...my voice control works just great...so many Easter eggs too...
 
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Using voice control it is sooooo easy to change temperature/fan speed/fan direction etc without ever touching the screen
For me, while voice control is a great option, it is not the method I prefer. When I am in my car, it is actually the most peaceful part of my day where I can get lost in my music (THAT is very important to me, but I am a weirdo). Doing anything via voice control is very disruptive to my experience.

But that's just me.