cabin air temperature sensor - wiring route help needed

william silver

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Autoglass replaced my windscreen and since then a catalogue of woes with my heating system.
What is the route for the cable from the heat sensor in the overhead to the heater/duovalve gubbins?
I ask because the autoglass guy told me he had cut a wire - "an old alarm wire guv" - on the internal face of the nearside front pillar when taking out the old windscreen.
The heater motor blew a fuse when he just left and I've replaced the duovalve as the classic failure symptoms showed i.e. no temperature variance - just cold or dead hot!
 

LNM

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If you're freindly with a merc spares department they have 3d diagrams to help identify parts, dunno if they do the same for wiring looms; might be worth a try.
 

prettyfly69

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Not entirely helpful but in a similair vain

Hi I have W126 electronic manual. For wiring Diagram (which if you see the queery below you'll se I also need to have a look at it) I can pulll out the appropriate diagrams and send to you.

But I'm also having problems with my temp control, it intermittently works or just goes to dead hot. (Haven't had it work in while) Where is the sensor(s) internal and external located? Could it be caused by a bad connection on the recirculate switch? In that It doesn't make that swoosh noise at the moment when pressed, could a losse connection cause the temperature to not vary?
 

dishmop

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I have had fun with the heating on my 126 since I got it. As you say, hot, or suddenly switches off, but if you switch the ignition offf and then on, the heating comes back on. Why oh why, cant they just stick to a simple old method like on a Morris Minor? The control for this is under the dash, passenger side. Remove either the interior of the glove box or the panel below the dash. Black plastic control box about 4" square. Find one from a breakers, but you wont know if that is any good until you try it. A good electronics man might be able to tell you whats wrong with your old one.

I would take the car back to the windscreen people and tell them to put right what they have screwed up. The wiring runs behind the sun visor area and down the windscreen pillar, but I dont know if its inside or outside the pillar. On My 380SEC the wire go to a fan motor behind the dash, but I think on a 280se 126 the motor is lower down.
 

dishmop

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Thinking about this a bit more this afternoon, just what is wrong with demanding your rights?

Some mooron has screwed up something on your car. If he didnt know what it was he shouldn't have touched it. If you got somebody in to do your garden would you be pleased if the bloke cut everything down because he didnt know what they were? Go back to the windscreen company and demand that they rectify the it and go and see your local trading standards officer.
 
OP
W

william silver

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  • Thread Starter
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  • #6
wiring for heating system

Fitted new cabin sensor and this seems to have cured the problem. This sensor is located in centre front overhead console with light in by rearview mirror. The sensor operates the small sniffing fan located on the nearside bulkhead by the battery which then instructs the duovalve to open/close to vary temperature. So it seems the Autoglass guy was right after all.
Isn't it easy to wind yourself up if you're fussy!
Thanks for your responses.
 


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