My 1995 C280 has begun to make a very high pitched squeeling noise when the air conditioner or the heater is being run. The noise itself persists independent of the speed of the fan, but when you turn off the system altogeter, the squeeling stops. Through a search on the shop forum, I think I've isolated the problelm as having to do with the interior temperature sensor. (AllData refers to it as an actuator, I think) I copied all that AllData has to say on the subject but unfortunately there's not enough information for me to proceed without some guidance.

"The in-car temperature sensor with aspirator blower (B10/4) serves for measuring the temperature in the vehicle passenger compartment.
The in-car temperature sensor is equipped with an aspirator blower which continuously sucks air out of the vehicle passenger compartment for measurement of the temperature.
It is connected to the pushbutton control module by a separate electric lead.
The aspirator blower provides continuous circulation of the interior air around the in-car temperature sensor to ensure a high degree of control accuracy."

Can anyone tell me if it sounds like I'm on the right track? And what I need to do to repair/replace or otherwise fix the problem? I'm not a mechanic, but I am used to doing some of the simpler tune-up and brake repair type of jobs.
Thanks, Bob

Well, at first blush it sounds like the blower fan motor, but if the noise is independant of it's speed, then maybe not.

The interior temp sensor uses a little fan to draw in air from the interior. It runs constantly while the ACC system is "on." The fan bearings might be going south, causing the noise. It's located (think 1995 is the same...) on the overhead console. Shouldn't be too big a job to change out...

Sounds like you are on the right track.

Does the ACC function normally otherwise?

__________________
John Shellenberg
1998 C230 "Black Betty" 240K

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I also have that squeeling sound coming from my center console area on my c280.

I have no idea what is happening but i do know that my ac will cut in and out from the center vents now.

Please do post back with any findings.

I had that noise too on my '94 C220, it came from under the glove box, passenger side. So it pointed be to the blower/regualtor. I took it apart and lubed the bearings. No more noise.
Where is your noise coming from ? If you suspect the aspirator blower, the noise would be then coming from the overhead console (dome light etc...).

The noise is coming from the center console area.

I will investigate under the glove box as well.