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Heat / HVAC on 7.0 - poor performance?
- Thread starter rdrcrmatt
- Start date
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- Model S User Interface
I tried this tonight for the first time since my heat was fixed. I can confirm that not only does it show HI heat but it is very hot and the fan goes up to 11. I'm on .77 and I started from a cold car.
mknox
Well-Known Member
When you say "fixed" what did they do, exactly? Kevin at the Mississauga SC asked me how my heat was when I stopped by last Friday and I told him that it worked... just poorly since v7. I get heat in the car (so the heating elements are working), but the fan speed is way too slow (2 or 3) and as I drive the car gets noticeably cooler even though it does warm up initially. And I also noted that stage 2 defrost (red icon) is only blowing setpoint temperature air (fan does go to 11) in spite of the fact that the temperature dials say "HI".
I have to get my 100,000 km "annual" done along with another DU replacement, so I may ask for whatever "fix" it was you got at the same time.
Kalud
Active Member
I still think the poor performance you are experiencing is related to the little aspiration temperature sensor under the armrest. Hope they can do something, or simply add a
#ifdef NO_ASPIRATOR_SENSOR
#define MIN_FAN_SPEED 5
#endif
My 25XXX VIN Classic has heat and fan goes to 11 when its cold then quickly goes to 5 for a little while and then settle down to 2. When it gets humid or on the verge of fogging it switch to foot & windshield, increase fan to 5 or 8. I wish we could meet to compare both cars, I genuinely would like to feel/see the difference and fix it (if we could). I always leave everything on auto and temp set at 21.5C and never feel the need to touch anything... Hope they can fix that for you (and others). They should be able to get some feedback from EAP users before getting issues like this on large VIN range...
mknox
Well-Known Member
Mine's a bit more "classic" with a 6XXX VIN range and no center armrest aspirator. Prior to v7 it also would initially raise the fan speed quite high (not sure if it went all the way to 11) and then would gradually settle down. Even then, I felt it would settle down too slow and kept the right scroll wheel set to Fan Speed so I could bump it up as needed. It could just be me. I like a little more air circulation, and 2 does not seem to move any air around in the cabin at all from where I sit. But since v7, the fan may initially go to only about 4 or 5 if it's really cold and then it quickly goes to 2.
I used to find I could leave everything in Auto and just play with the fan speed a bit, but now, I have to manually adjust all the settings. I even have to start bumping the temperature up after a half hour or so to stop the gradual downward temperature creep that starts happening.
The details on my fix are further up this thread. Tesla called it a replacement of the DC-DC converter. I have no idea how this affects the heating system but I had only cold air in all modes one morning after heat previously worked (although differently) on v7. Overall, I would agree with you that v7 has definitely changed the heating algorithm. I now need to set it at 21C where I previously had it at 19C and I've also noticed that it will not heat all of the time when it probably needs to on the colder days.
My last update was specifically about your experience with the front defrost on "double-tap" HI mode. You mentioned that you were getting cold air and I am definitely getting hot air and an 11 fan speed. The fix I mentioned wasn't specific to this - it was that I had no heat at all.
While this may not be the same as you are experiencing, I wanted to ensure my statements were clear in case they can help you or someone else.
By "slow" I assume they mean measured in days because on my 2.5hr commute the cabin was not appreciably warming up, unless I crank it to 78-80. I just got .77 so I will see if that helps.
JenniferQ
Active Member
I'd like to know if that helps, as it was 75º here today and I can't figure out how to see if the heat works?? But I will need it when I travel next week to colder climes.
mknox
Well-Known Member
Right. I did see that, but didn't scroll up to see that it was you! You had no heat at all which does seem to indicate some sort of physical problem. Glad they got that fixed for you.
It's certainly bizarre. I will find that the car initially heats up fine (albeit with a bit of manual override intervention on my part) but as I drive it gradually gets cooler and cooler. I noted yesterday that no matter what mode I'm in, there will be a little bit of flow to the defroster vents. Not sure if it always did that. But with temps near freezing, the glass will be cold and this little bit of air movement is creating cold drafts throughout the car.
Kalud
Active Member
The reason they replaced the DC-DC converter is because the DC-DC converter also serves the function of the front high-voltage junction box. It feeds the 400V from the battery pack to the PTC heater used to head the cabin. It also feeds the AC compressor for example. So I guess while investigating the issue they found that for some reason it was no longer sending power to the PTC heater so they replaced it.
- - - Updated - - -
Here's a picture of what it looks like and the HV connections to the PCT Heater (marked CABIN HTR), Battery coolant Heater and Compressor.
Original version
Latest version (on the left)
Last edited:
Not sure how turning the fan down would save energy. If they are putting kW into the heater element, the energy is going somewhere. The fan evenly distributes it through the car.
Just staying in the heater box? Seams like that may end up raising the heat element temp high and make it more susceptible to burning out.
Just staying in the heater box? Seams like that may end up raising the heat element temp high and make it more susceptible to burning out.
mknox
Well-Known Member
I agree, and thought it was odd when I was told this as well. It makes my car feel like there is a convection heater under the dash and heat is just rising up from there as opposed to being blown around.
Many (including me) have reported "burning smells". I am used to getting a burning smell at the beginning of each winter which I attribute to dust burning off the elements, unused all summer. It would go away after a day or two. But now, if I don't bump my fan speed up manually, I still am getting the burning smell. I hope the elements are robust enough that burnout is not a problem. When I'm in the car, I can turn the fan speed up, but when I use the app to pre-heat, it sets the system to Full Auto until I get back in.
No, you put less flow through a PTC heater, it draws less current.
However heating the cabin slowly is not an energy saving unless you're saving energy because the car is never warm, and that's not an acceptable answer.
mknox
Well-Known Member
Less air flow through the heater causes less current draw? Not sure how that would work unless there were additional sensors in the heater box to accommodate this.
Kalud
Active Member
Positive Coefficient Heater means that the internal resistance increase as it heats up, so technically you are both right. Less air flow, the internal unit heats up and as it heats up the internal resistance increase (limiting the actual internal heat generation).
mknox
Well-Known Member
My car was in for service last Friday and there was a new firmware notice on the 17" when I picked it up. Oddly, it was 2.7.77 which is the same version that was on the car when I took it in. Nothing new since then for me...
green1
Active Member
Now on 2.9.12, haven't tried it much yet, but the climate control seems to be significantly more aggressive then before. (that said, I've only driven a couple hundred metres since I got the update)
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