AC Sunlight Sensor

[oldcodger]

Hi,

Have got the later style 2006  Digital control panel for the AirCon etc and noticed a problem with the Ventilation / AirCon the other day in that it was still letting warm air in when set to cold.

Can hear the damper being operated but not when it goes down below 22c

Ran the Diagnostics and it gives Error 21  AC Sunlight Sensor ,  which was not present a couple of months ago when checked after a recharge.

Seems its that little black dome thing on the top of the  drivers side of the dash board, right under the bottom of the windscreen.    ( always mistakenly thought that was something to do with the remote control )

Anyone know anything about this sensor,  can it be tested /bypassed and how to get it out ?

Seems the cabin temp sensor works ok as it controls thing ok in Auto mode, but  no real idea how a Sunlight sensor works with the AC system ??

[DeTomato]

From what I understand, the dome is an ambient sunlight sensor which amplifies the Climate Control / AC to boost on AUTO when it's very bright sunlight. Easy way to see if it is working is to shine a strong light onto the sensor and seeing if the A/C boost is working on Auto when pushing the Auto button and having the A/C on 16 degC or Cold.

The dome can be prised out from the dash if careful, but means using something curved, very thin and strong to push in the side clips which prevent it coming out from the dashboard top. Otherwise it is also accessible by removing the dashboard cover in front of the sensor I believe (though not sure on your specific model).

[oldcodger]

Hi,

Thanks, yes that does make sense though cannot say I have noticed a sun related boost like that before, though do not use auto mode that much.

Will give it try tomorrow if its sunny enough or with a led torch and see what happens.

Think it sounds like I have two problems as doubt that sensor is going to affect the damper flap closing off fully ..?

Might be worth looking behind the control panel and seeing if the wiring connectors are sound first,  if it gets past its mot in the morning !

Had 11 years totally trouble free driving from it, but seems this year its decided to let go...

[DeTomato]

This is how it looks if you have this type like in my Corolla. The two lugs either side need to be compressed to get it out, but take care not to damage the dash top. Always find problems just before a MOT too - Murphy's Law  but don't think the A/C is a MOT failure problem. The damper not closing is more mechanical I would think, probably awful foamy seal stuff getting misplaced and not letting it settle into place correctly.

Light-Control-Sensor-for-Toyota.jxr

[oldcodger]

Hi,

Thanks again,  seems if its the same sensor its used on many models, seen it on a uk site for a land cruiser as a genuine part at £95 !  though Ali Express doing them for £3 !

Have tried twice using the Toyota paid for EU  tech sheets in the past, but just cannot make sense of their files or open them properly,  are they so difficult to use or just me ?

[DeTomato]

Toyota have done a recent update of all the parts on their site with schematics and mouse overs to see part numbers etc and it is really great to use. They're not all logically in the right place but at least you can find something eventually if you go through enough diagrams specific to your model. I use IE 11 and Edge which open these ok. Mouse over and clicking on a part number gives more information which is really good. But, as to your specific requirement for a genuine ambient sensor part, when I checked the screen defroster which contains this on my Corolla dash top, it does not list this part at all, even though it is a standard fitted part.

[roks]

I dont recall seeing any sensors on the dash although I have electronic a/c control....must take a close look next time.

[DeTomato]

Easily missed  My Corolla ambient sensor is sunk into the end of the screen defroster towards the drivers side up by the windscreen. Wasn't aware it was there until I cleaned over the dashboard last week.

[oldcodger]

Hi,

Unable to test the sensor today as its been totally overcast and a torch does not seem to have any effect, perhaps not the right  frequency as otherwise street or head lights could affect it at night ?

Have looked under the dash as I needed to check on the condition of the damper flap actuators and they do seem to work over the full range ok so not sure why its letting some warm air in when on the Cold setting, though its no enough to affect things when the AC is on and cooling.

Also able to look up under the dash board with a mirror and torch and can just see the screen vent underside, but not enough to see the sensor and there is no way you could reach up there anyway with all the metalwork around.

Equally it looks a real challenge to get the sensor out from the top, plus it could easily lead to damaging the dash covering.

As both problems are not dramatically affecting the heating or cooling think its probably best to leave well alone for now and hope it does not get worse.

One ray of sunshine though, got though the MOT ok, not even an advisory,  and ironically he complemented me on the handbrake force, which from my other recent post where I had all those problems with the new hand brake shoes and drum/discs, which I had to remove and refit the old parts for the test. 

 

[DeTomato]

There must be some special tool to remove the sensor perhaps. Quite understand the problem of even seeing it from removing the front dash cover because things like the air ducts etc must be large enough to get any hands in there. I suspect my own will cover out when the windscreen defroster is removed because it is located in the end of it. But suspect the plastic is bristle with all the years of heat on it so not going to attempt it unless it fails. One thing I did think about is whether there is a fuse or relay for this sensor which may have failed? 

[oldcodger]

My car is due this airbag recall, suppose I could ask them to replace it then, though doubt they would fit my own ali express part .

Cannot say  have seen any sensor with its own fuse or relay, sensors normally direct connection to avoid signal loss.

Have seen a US 2004 diagram but it does not show that sensor  in the AC section,  they call it the Light Control Sensor and it shows up in the headlight diagram, connecting to the Daylight running module.

 

 

[DeTomato]

Day Time Running lights are an optional extra on the headlight stalk. Not sure they're on the same sensor because it's usually in the mirror or somewhere? Needs further investigation...

[oldcodger]

Hi,

Well 6pm and the suns only just come out today,  beaming low and straight on to the dashboard, and it gave error 00 , all ok.

Keep in that mode and rolled the car out of direct sunlight and it changed to error 21,  went back into sunlight and it change to 00.

So wondering if the sensor is really faulty, or is that just its normal action /error reporting   ?

[DeTomato]

Question is, did the A/C amplifier kick in when on auto and set to boost COLD air into the cabin? If so, it must be working.

[oldcodger]

4 hours ago, DeTomato said:

Question is, did the A/C amplifier kick in when on auto and set to boost COLD air into the cabin? If so, it must be working.

No, didn't have time to test with AC , will try that soon.