aircon set to AUTO

NemesisUK · December 21, 2018

As I posted, at start-up the system will be in recirc to speed up heating or cooling. It will also switch to recirc in traffic when the NOx sensor detects high levels. It will also switch back and forth on a trip simply to maximise heating and cooling efficiency. I don't use ECO mode, ever.

Steve44 · December 23, 2018

Mine is set to Eco and doesn’t switch often between outside and recirculated air. I’ve only seen it do it in the summer when it tries to cool the car quickly and switches to recirc to do so. On cold mornings it doesn’t do likewise to warm faster. I’ve never seen it change according to pollution levels.

Andrew888 · December 23, 2018

Auto Climate depends on 3 sensors - Outside ambient (which shoild be ok), Solar/Sun ray sensor (this measures the intensity of the sun, sensor is by the windscreen heater vents (passenger side) and looks like a little black dome and you'll also have a cabin sensor which is by the left hand panel under the steering wheel (its like 2 or 3 slits in that panel) and depending how old the car, it could have got dusty, you will need to take that panel off and get to the sensor behind it and lightly vacuum it out as dust etc gets in there. if all else fails Solar/Sun ray sensor could be iffy.

Thackeray · December 23, 2018

32 minutes ago, Andrew888 said:

Solar/Sun ray sensor (this measures the intensity of the sun, sensor is by the windscreen heater vents (passenger side)

That's interesting. Didn't realise it had this sensor. The climate control is more sophisticated than I thought. I went and had a look to see if my car has this and sure enough, there's the little dome that I'd never noticed before next to the demisting vents. I assume that when the sun is intense the air from the face vents would be made cooler than usual to compensate for the heat of the sun. Maybe the air conditioning would be turned on, too, if it was off at the time.

Herbie · December 23, 2018

1 hour ago, Thackeray said:

Solar/Sun ray sensor (this measures the intensity of the sun, sensor is by the windscreen heater vents (passenger side)

1 hour ago, Thackeray said:

That's interesting. Didn't realise it had this sensor. The climate control is more sophisticated than I thought.

I'm not sure that it is.

Yes, that little dome is a sensor but it's a photocell measuring light levels for the auto lights, not a sun ray sensor for the climate control.

Andrew888 · December 23, 2018

That sensor is dual function, just like the Hondas. Technology nothing special there.. Also the auto headlight main sensor is by the rear view mirror.

ColinBarber · December 23, 2018

On 12/21/2018 at 7:09 PM, NemesisUK said:

It will also switch to recirc in traffic when the NOx sensor detects high levels

The IS doesn't have auto recirculation based on air quality, I didn't think the RC has that either. Is there a three way option on the recirculate button including auto?

Thackeray · December 23, 2018

35 minutes ago, Andrew888 said:

That sensor is dual function, just like the Hondas

Do you mean it is used to turn the lights on, as well as sense the strength of the sun? Are these the two functions? Does it work in collaboration with the sensor by the mirror?

NemesisUK · December 23, 2018

47 minutes ago, ColinBarber said:

The IS doesn't have auto recirculation based on air quality, I didn't think the RC has that either. Is there a three way option on the recirculate button including auto?

From my handbook -

Switching between outside air and recirculated air modes
Press .
The mode switches among (recirculated air mode), automatic and
(outside air mode) modes each time the button is pressed.
When the system is switched to automatic mode, the air conditioning system operates
automatically.
The indicator above the selected button comes on.

Outside/recirculated air mode may automatically switch depending on the temperature
setting or the inside temperature

From the Lexus EU tech doc for my car

Also as posted above the light sensor on the dash top is dual function, providing the a/c amplifier control with light intensity info.

Thackeray · December 23, 2018

2 hours ago, NemesisUK said:

From the Lexus EU tech doc for my car

That's interesting. What about the IS300h? Is there any documentation about whether it works in the same way as the RC300h? It doesn't have an Auto option for switching between recirculated and outside air.

Andrew888 · December 23, 2018

3 hours ago, Thackeray said:

Do you mean it is used to turn the lights on, as well as sense the strength of the sun? Are these the two functions? Does it work in collaboration with the sensor by the mirror?

Yes it works in collaboration for 2 functions. To sense check the auto climate setting i.e. I think fan speed and also for the headlight sensor. It gives off different voltages 0-5V depending on intensity.

ColinBarber · December 24, 2018

23 hours ago, NemesisUK said:

From my handbook -

Switching between outside air and recirculated air modes
Press .
The mode switches among (recirculated air mode), automatic and
(outside air mode) modes each time the button is pressed.
When the system is switched to automatic mode, the air conditioning system operates
automatically.
The indicator above the selected button comes on.

Outside/recirculated air mode may automatically switch depending on the temperature
setting or the inside temperature

From the Lexus EU tech doc for my car

Also as posted above the light sensor on the dash top is dual function, providing the a/c amplifier control with light intensity info.

Nice, unfortunately the IS doesn't have this.

ColinBarber · December 27, 2018

On 12/23/2018 at 12:27 PM, Andrew888 said:

Also the auto headlight main sensor is by the rear view mirror.

No, it is by the drivers A pillar on the dashboard.

Andrew888 · December 28, 2018

20 hours ago, ColinBarber said:

No, it is by the drivers A pillar on the dashboard.

Indulge me as I can only see a speaker by the drivers A pillar?

ColinBarber · December 28, 2018

3 hours ago, Andrew888 said:

Indulge me as I can only see a speaker by the drivers A pillar?

well not directly next to it a bit further into the middle of the vehicle. It's actually on the passenger side, I was looking at a LHD diagram but it is swapped over for RHD vehicles. The sensor is also used for the Solar loading sensor of the A/C - in previously generations of Toyota vehicles there was always two separate sensors, it is combined on newer ones.

Herbie · December 28, 2018

On 12/23/2018 at 12:27 PM, Andrew888 said:

Also the auto headlight main sensor is by the rear view mirror.

Is that not the rain sensor?

Andrew888 · December 28, 2018

1 minute ago, Herbie said:

Is that not the rain sensor?

Theres 2 in the rain sensor part.. the black square is for the wipers and theres a tiny lens underneath that. Lexus tested these components as I was having "blue sky syndrome" with my auto setting as they were activating in really bright weather.