Can someone tell me what the 4 pin sensor located between the distributor and the air horn is, what it does, and how I can test it.

I have a good photo of it but was not able to load it with this question so I could use some help learning how to load a photo also...

With the engine cold, the CCU blower fan starts after ten seconds when dial setting is calling for additional heat, but literature I have read says there is an "engine kill switch" (single pole) that should keep the fan from starting until the engine reaches 35 deg C.

Does my car have this switch and where would it be?
I dont really need more heat right now, just thought I ought to get this fixed before winter...

Thanks, CR

There are 3 motors on a 89 420SEL that move air, Aux fan, HVAC blower, and the aspirator fan for the incar temp sensor.

Is a CCU blower fan like any of those?

I'm not much on PC training but to load an image you first need to size it to fit with an image program. I forget the limitations but 700x700 is somewhere close. Once the image fits the size requirements it then must have only so much content 50 or 60k if I recall. My image program has something called a jpeg optimizer. With the image loaded I go to the optimizer and pick the compression necessary to fit the requirement. I then save the image where I can find it and I go back to the mercedesshop Post Reply screen such as I am using to write this. I then click on the browse button next to the attach file block. This browser allows you to find your file and open it to this post. Then hit reply.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

The CCU (Climate Control Unit) blower I referenced is the blower that circulates air (heated or cooled) throughout the interior of the car, so I guess that would be the HVAC blower.

I will once again try to post that photo.

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