Cabin temperature sensor.

Corned

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Having learned something yesterday, it set me thinking.

My car sometimes doesn't seem to really belt out cold air as it sometimes can. In the recent past I have checked the overhead console temp sensor to ensure it is not full of fluff and other detritus, which it was not.

However, I now understand that there is a second temperature sensor in the dashboard - the little circular grille thingie just left of the steering column.

Can anyone please tell me how to gain access to it to make sure it is serviceable and working correctly?

Many thanks.
 
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Corned

Corned

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Hmm. I'm guessing that's a 'no' then...
 

Miffy

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I'm surprised that nobody yet has said ' get it plugged into Star at an Indie' :rolleyes: :rolleyes: :rolleyes: ;)

well you have just said it :) and what a good idea, plug into star, get the error code, F6 into wis for further help.
 
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There is nothing wrong with it necessarily! I just want to see if it is full of fluff, etc, which might stop it functioning properly.

Because these things ususally have a tiny little fan to draw in air over a thermocouple, they also draw in whatever airborne particles happen to be passding at the time, and over time it all clogs up with fluff.

I have had cars in the past which had these so full of fluff you could have woven a little carpet for a dolls house out of all the fibres collected inside.

All I want to know is whether I can carefully pry the thing out of the dash with a screwdriver, or if I have to go in from underneath the footwell - that kind of thing.
 

whitenemesis

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If it's anything like the one on my CLS, it's accessed from underneath after removing the lower cover. Grip the sensor from behind and turn it clock-wise (looking from the front). It'll come away from the visible part and you can then remove the electrical connector.
 
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Thanks, WN - I'll get the lower dash panel off and have a look!
 
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Progress already!

Dropped the lower panel and reached up towards the temp sensor. Only had to reach a couple of inches and the sensor itself, dangling on its wires, was found loose behind the dash. Nowhere near where it should be!

And it's filthy...
 
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Result!

Sensor now clean and back in place, and the tissue paper suction test passed.

However.

The only problem that I can see is that the bezel (the grille you see embedded in the dash) is distorted and broken in places, so the sensor is not properly located. I can see this being a temporary fix as the sensor will surely drop out again in time. There is no part number visible on it either.

Thanks again, WN. You were spot on. The sensor 'bayonet's onto the grille bezel from behind, just like a bayonet lamp. The bezel is just a push fit in the dash.
 

whitenemesis

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You could try part # A2118300618 but you'll need the ES2 code for the correct colour, the parts dept would need the VIN. It's approx £23 from MB
 
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Blimey - £23 for approx 5 grammes of ABS plastic. :rolleyes:

Superglue to the rescue then!
 

Nailzy

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I still havent been able to get to mine. I can never get the lower panel out! Seems to be wedged in behind the accelerator somehow but wont slide out.
 
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That footwell panel is very tight. It also locates, on the inboard side, onto the outlet duct for the footwell air supply from the heater. What you have to do is remove the 3 torx screws, plus the large white plug at the back - it just pulls down - and then pull down the panel at the outboard edge first. Then go to the inboard side and try to bend it slightly to pull away from the heater outlet duct. It is tight, but it can be done. Don't pull too hard or too far either, as there are various electrical connections onto various electric and electronic components fixed onto the top of that panel.

Once the inboard edge is free, you can lower the whole panel sufficiently to put your arm in and up into the void, and you can feel your way up to the area where the temp sensor is located.

In my case, that area was vacated, but my arm was bumping against something swinging about hanging on a little wiring harness...
 

Benz17

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Having learned something yesterday, it set me thinking.



However, I now understand that there is a second temperature sensor in the dashboard - the little circular grille thingie just left of the steering column.



Many thanks.

Have had the car for over 2 years now, I was always curious what the above was, now I know thanks for that:D
 
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Have had the car for over 2 years now, I was always curious what the above was, now I know thanks for that:D

LOL - could be worse - I've spent the last 4 years talking into that bit on mine... :Oops:
 

Nailzy

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My understanding is the mic is part of the rear view mirror assembly
 
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^ Correct - the four little grilles underneath the mirror each have a microphone in them apparently.
 

Nailzy

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That explains when I've got a car full of colleages having a conference call no-one moans about not being able to hear us I guess :D
 
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Quick update.

So far the 'repair' has held. The little grille by the steering column still passes the tissue paper suction test.

Of much more significance however is the observation that the cabin temperature is much better controlled than has ever been the case in my ownership.

I have always been disappointed with the air temperature output from the vents when the cabin has been hot - for example today, parked up in the sun all day. Yes, it has been cool, but never a good biting cold. I thought that was as good as it could get, particularly after regassing the system and making sure everything (as far as I could tell) is as it should be.

However, I can say that now it actually hurts to leave my hand in front of the centre dash vents for any length of time. There's the biting cold I've always been missing!

The temp sensor, swinging around on its own wire in the under-dash space all these years, has obviously thought that the temp under there was just fine.
 

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