Cabin temperature sensor reading incorrectly

[Cicoria]

Today I left my car charing in the supermarket park while I was shopping for groceries and since it was parked under the sun for 1 hour I figured out I could activate the remote AC to find a cooled cabin and boot.

The AC started and operated at 22ºC as per Lexus Link+ for 17 minutes (the timer allows maximum 20 minutes) but when I got to the car the cabin was hot. 😑

When I turned the ignition on, the thermometer on the dashboard was reading 19ºC, under the hot sun, while the real temperature outside was 25ºC, so the cabin would’ve been at least 30ºC at minimum, and while I drove back the temperature on the display increased to 21ºC.

The problem with this is that the AUTO A/C relies on that thermometer to operate, and that’s the default mode the climate control operates via the app (you can’t operate the AC in manual mode choosing the fan speed and other settings), therefore if the cabin thermometer reads 19ºC when I chose to start the remote A/C set at 22ºC, the system simply won’t operate because it thinks that the cabin is colder than what I asked.

Anyways, I can’t go lower than 18ºC on the app, not even to the LO setting.

This **** right here was exactly the same with my previous UX 250h, minus the remote function of course.

Can it be a faulty sensor or it’s just another annoying Toyota feature that I need to add to the list? The AUTO feature is rubbish, I always use the climate in manual mode.

[NemesisUK]

I always thought the temperature displayed on the dash was the ambient air temp, not the cabin temp and nothing to do with the a/c. If one sets the climate control to 20c the system will operate to achieve that temp irrespective of the outside/ambient temp by heating or cooling.

[Cicoria]

50 minutes ago, NemesisUK said:

I always thought the temperature displayed on the dash was the ambient air temp, not the cabin temp and nothing to do with the a/c. If one sets the climate control to 20c the system will operate to achieve that temp irrespective of the outside/ambient temp by heating or cooling.

If you set 20C in manual mode (so AUTO button off and manual ventilator speed + manual ventilator zones set) then the AC blows air at that specific temperature, like a home AC unit, but if you activate AUTO then everything relies on the system to set every parameter using the cabin sensors such as the the temperature sensor and light sensor so that the unit can “see” which directions the sun comes through the windows and windshield.

This is the problem I have, since the remote AC is only operated with the AUTO mode, if the sensor reads a wrong temperature then it won’t work properly. 
 

I never use AUTO mode because on Lexus and Toyota cars I find it useless and very slow or inaccurate, so I always use the manual mode which defeats the purpose of having a climate control unit…and yes I’m aware that there are 3 “speeds” ECO/NORMAL/FAST to set the AUTO mode in, but the remote AC is set to NORMAL as default each time you send the command, so you can’t do anything to speed up the cooling/heating process.

In any case, I expected to find a cooled down cabin but it wasn’t even remotely warm after 17 minutes of AC running (supposedly), it was still hot. There’s also no way to skip the 20 minutes timer, despite having the car actively charging up, but then again I see the safety mechanism of preventing the Battery to be drained if there wasn’t a time limit and you forgot to deactivate the function…but then again if the car is connected and the Battery is charting then it can’t be drained to 0%. 

[NemesisUK]

Never had a problem with the a/c on auto, the system copes very well with changing conditions even changing the airflow side to side with the direction of the sun.. The climate concierge even set the seat heating/cooling very efficiently ..

[Cicoria]

2 minutes ago, NemesisUK said:

Never had a problem with the a/c on auto, the system copes very well with changing conditions even changing the airflow side to side with the direction of the sun.. The climate concierge even set the seat heating/cooling very efficiently ..

I’m happy for you, I’m not fond of how the system works on Lexus cars though, but then again I’m a nostalgic of manual AC without touch screens and tons of buttons.

The best automatic AC system I tried was on a Seat Ibiza, the previous gen to the current one on sale, it was mono zone but it was powerful and simple, immediate. 

[stepppy]

13 hours ago, NemesisUK said:

Never had a problem with the a/c on auto, the system copes very well with changing conditions even changing the airflow side to side with the direction of the sun.. The climate concierge even set the seat heating/cooling very efficiently ..

Same here, seven years in my previous Prius used to have the CC set to 21 Auto with the compressor set on Eco and found it worked like a charm.  The only time I would change the temperature is in the winter where I would change it to 22.

Only had my NX since March, but so far I use the same settings and it's working as expected.

I haven't tried the remote feature, so I cannot comment on how that works.