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What's this microphone/sensor looking thing ?

22K views 12 replies 5 participants last post by  Vortecpwr 
#1 ·
It looks like it could be a microphone, perhaps for the voice commands. I know the telephone mic is up near the sunroof controls and internal lights (I saw that in the user manual PDF), but this one doesn't seem to be in there.

I wonder also if it's something to do with the climate control (sensor of some kind).
 

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#4 ·
Unstable temperature in a W212 (E350) - Interior sensori

Hi Konigstiger,

Heating Ventilating and Air Conditioning lower interior temperature sensor ?
Do you happen to know if there are other sensor to regulate the interior temperature ?

It is my understanding that when ever the A/C is not delivering the right air temperature then it may well be that this sensor (or some other in the cabin ?) is dusty to the point that it cannot measure properly the cabin temperature and therefore it blows hot or cold air in a hieratic manner.

This is the issue I am facing with my W212 2010 Sedan. While I am setting the temperature to, let's say, 19° Celcius it blows hot air in the cabin and bring it far over the requested 19°C. It blows this hot air until I switch to "Low" on the A/C. In fact, I am forced to play with the temp switch every 5mn in order to keep the cabin temperature "balanced"... Not really a situation what one would expect from an automatic temperature regulation system...

This phenomenon appeared very recently and I can't remember of any event or command alarm which would make think about something was going wrong.

I have been through many forums around but couldn't find too much about this situation on a W212. Not sure how to make a solid diagnostic about the root cause of this issue nore I could find a way to access to this sensor to check/clean it.

Any idea or suggestion ?

Thanks in advance for your interest and support
 
#5 ·
Hi Konigstiger,

Heating Ventilating and Air Conditioning lower interior temperature sensor ?
Do you happen to know if there are other sensor to regulate the interior temperature ?
Yes - many...:) In fact nearly ALL the a/c temperature sensors are there to regulate the interior temperature. Here is a list, taken from my WIS.

B10/31 a/c air outlet temp sensor - left side. (input to a/c panel N22/7)
B10/32 a/c air outlet temp sensor - right side. (input to a/c panel N22/7)
B10/35 footwell air outlet temp sensor - front left side. (input to a/c panel N22/7)
B10/36 footwell air outlet temp sensor - front right side. (input to a/c panel N22/7)
B10/38 footwell air outlet temp sensor - rear, up to 02/11. (input to a/c panel N22/7)
B10/4 interior temp sensor. shown in photo above. (input to a/c panel N22/7)
B10/6 evaporator temperature sensor. (input to a/c panel N22/7)
B11/12 dew point sensor, up to 05/10. (input to a/c panel N22/7)
B11/4 coolant temperature (input to ME-SFI control unit N3/10)
B12 refrigerant pressure sensor (input to front SAM N10/1)
B14 outside temperature sensor (input to front SAM N10/1)
B31 emissions sensor. (input to a/c panel N22/7)
B32/3 sun sensor. (input to a/c panel N22/7)
B82 interior humidity/temperature sensor, from 12/09. (input to a/c panel N22/7)
 
#6 ·
Hi Keyhole,

Thanks for the quick answer and ... the long (!) list of sensors
This is very interesting
I guess that any of those sensors can contribute to the temperature instability that I am currently facing

Is there a way to identify which of those sensor is causing the issue ?
Eg.: Is there a way to get to a kind of menu where you can read the actual temperature at each of the sensors ?

I did find that there is some hidden function on the W211 A/C unit which does allow one to get to the actual temperature information for each of the sensors related to the A/C but the "code" used to access this information doesn't work for the W212 A/C unit

Would someone happen to know if this information is also accessible on a w212 A/C unit ?

I guess that there must be a better way to identify the faulty sensor than finding and testing those one after the other

Any idea or suggestion is welcome.

Best regards
 
#10 ·
Keyhole, Koningstiger,

Thanks much for your support and suggestions. I am going to try the two perform the two basic tests proposed by Keyhole they are easy and meaningfull. I'll then visit my dealer if in the mean time I can't find the root cause of the issue.
I'll let the forum know.
Could be usefull to next W212 owner wondering about his A/C hieratic behavior
Cheers
 
#11 ·
Dear all,

I did perform the recommended 2 tests (small piece of tissue in front of the sensor grille on the dash to see if the fan is still working and then a gentle pass with a vacuum cleaner) and recognized that the piece of tissue was somewhat "attracted" by airflow but decided to go on with the vacuum cleaner operation and since then it looks the A/C is back under control.
The cabin temperature is regulated and seems to correspond to the temperature requested on the display unit.

At the end, I am not really sure what was wrong as I wouldn't expect the sensor was covered with dust (eg.: small piece was attracted + I do not smoke + the area I leave is not dusty + the car is kept clean regularly).
Anyway, I am happy that the problem is solved for now.

There is a last step I will perform anyway : showing the car at my MB dealer and ask for a diagnostic. Will see then if there was any error code logged. Will report here if I get meaningful information

FYI, I am now with an other issue which did appear 2 days ago : the media unit scrolling knob rotation is not working anymore. Looking at the forums it looks like I am a victim of the "well known" little piece of plastic which brakes so easily on all W204 and W212 after more or less 4 years of service.... As I could not find any video explaining how to dismount the unit in a W212 I will then probably post something on the appropriate forum in the coming days/weeks as I suspect I am not the only W212 owner looking for this information.

Thanks again for your support & best regards

NB: I could get access to the WIS/ASRA information and
 
#12 ·
Looking at the forums it looks like I am a victim of the "well known" little piece of plastic which brakes so easily on all W204 and W212 after more or less 4 years of service.... As I could not find any video explaining how to dismount the unit in a W212 I will then probably post something on the appropriate forum in the coming days/weeks as I suspect I am not the only W212 owner looking for this information.
If you do that, please attach a photo showing exactly what control knob is broken. The EPC uses surprising titles for some parts. Also, be prepared to discover that the individual part is not available. On my CLK, a broken glove box latch means that a complete door is required.....:frown
 
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