I think the car can't keep up with the fan speed and heat generation at that setting. Seems like a limitation of the car. Hopefully I won't have broken sensors/parts in the future on top of that.
I think not, please read below why.
Update:
Okay, so my car (M3P MY21, 836xxx) finally had the pressure sensors replaced/changed at the Tesla Service Center, only about two weeks ago. I asked about possible subsequent failures, the service rep told me that at least she hasn't had any car return for another replacement as far as her history goes.
Just as a reminder, these were the exact parts:
Code:
Correction: Sensor - Subcool - Pressure and Temperature - High Pressure (Remove & Replace)
Parts Replaced or Added Part QTY.
PT SENSOR, LOW PRESSURE(1510048-00-B) 1.0
PT SENSOR, HIGH PRESSURE(1510047-00-B) 2.0
Correction: Sensor - Pressure and Temperature - Low Pressure (Heat Pump) (Remove & Replace) Correction: Sensor - Pressure and Temperature - High Pressure (Heat Pump) (Remove & Replace) Pay Type: Basic Vehicle Limited Warrant
Even before the replacement of the sensors, I've had no issue(s) with "TURN ON CLIMATE" and getting the car heated up (when stationary) even beyond -20'C temperatures for an extended period of time. However, after taking the 1.000 kilometer drive south (during which the issues of not getting enough heat could be felt to the bones) and having had these sensors replaced, I hadn't gone on any longer trips with my Tesla. Hence, the issue hadn't been visible since.
However, now as I did another 1.000 kilometer drive north just this week (split to two days of driving, with outside temps ranging from -16'C to -26'C), the issue of not getting proper heat into the car was immediately back. But why, how?
Here's my hypothesis on the subject, as I had a good 18 hours of in the car during two days of driving. (Read: Enough time to test this into oblivion.)
- Everything is fine, when you remotely turn on the climate from the mobile app, especially when the car's battery is cold, as it turns on the heat pump AND starts preconditioning the battery
- Everything is fine, when you're driving to the nearest supercharger with the SC set as a destination on the navigation (as next stop), IF you're close enough to it (e.g. 40 kilometers away), as the car starts to precondition the battery automagically
- Everything is fine, if the car's battery is cold (somewhere below between +15'C...+25'C I will yet test at below what temp exactly), and the heat pump activates (you can hear the 'HURRRR'ing sound clearly, when it does)
- Heating doesn't really work when your car's battery is warm: This is exactly the point when cabin heating starts dwindling down, most visible when e.g. leaving a supercharger with the battery at +50'C. At this point, one needs to turn up heat to "HI" and reduce airflow power to ca. level 4 or less (+ turn center air flow OFF), which is quite quick in the cold weather when driving 100km/h. Surprisingly, most heat is delivered to the BACK (turn this on), but you really don't get more than +16'C inside and your hands will freeze on the wheel
- When heating doesn't work, your best bet is to come to a full stop, put the car in park-mode, use mobile app to "TURN OFF CLIMATE", wait for 15 seconds or so, "TURN ON CLIMATE" and have climate on "AUTO" hope to hear the heat pump activate. Caveats:
- The heat pump doesn't want to activate, if your car's battery is warm. In this case your best bet is to do the above ("HI" and 4 or less power, heating to the back on and airflow to windows & floor, not center) to get the inside cabin temperature up to +16'C (Car using less than 1 kWh on idle), do remember to set airflow to the back-- this is the most excruciating time to have to drive in the cold
- In semi-warm battery conditions (e.g. battery around +25'C), when the heat pump actually does turn on (but is operating at low power), turning from AUTO to MANUAL settings, the heat pump will disengage and turn off! When at this stage on AUTO, you actually can get more heat to the cabin for a pleasant drive. (Car using around 2 kWh on idle)
- After multiple tries (or battery at around +10'C), when the heat pump does actually get fully engaged in its task, it makes a much louder sound (and turning from AUTO to MANUAL doesn't turn it off anymore), this is when you can get all the heat in the cabin that you want at whatever outside temperatures, worked fine in beyond -20'C. (Car using beyond 4 kWh on idle)
<TL; DR> It seems that there is no problem for the car to generate heat in reality, not a hardware problem either, but perhaps some firmware update in between versions has broken/modified the heat pump interoperation with other heat sources (e.g. octovalve scavenging heat from battery) which are not sufficient in e.g. -15'C or colder conditions.
