funny noise, help...
 

ok, on my 96 300D, when I go to start the car, I turn the key, and as I am letting the glow plugs heat up, there is this kind of odd noise that seems like it is coming from the rear view mirror? It kind of sounds like when you first start up a microwave, how it is real low and gets progressively higher or faster? Maybe it is coming from the dash, but I just cant tell. Any thoughts???

Could it be the blower motor starting up? Is your climate control set to off?

Same year and model, and here in Jersey, when the temperature goes below 20 degrees outside, when I first start up the car, I get a noise similar to yours. It seems to be coming from the center dash area, so I am thinking that it may have something to do with the blower motor as the other member suggested. This sound seems to be temperature related, and is never heard at temperatures between 25-95 degrees. I plan to leave well enough alone, and live with it.

How loud is this noise you guys have?

On the roof console above the mirror is the air sampler. Its a small fan you might be hearing? For the first few years I owned the car I thought it was a microphone for the MB telephone.

That is it, it has to be. I checked tonight and it is coming from above the mirror. What exactly does the "air sampler" do?

The "air sampler" is an interior "cabin" air temperature sensor connected to the climate control system. The unit has its own built in fan to move air across the sensor. The unit should cost under $100 and is easily replaced by removing the overhead console and snapping it out of its plastic retaining clips.

David Roseman
Long Beach, Ca