little fan motor tube thing behind the glove box??? - Early W124 - PeachParts Mercedes-Benz Forum

777funk · #1 03-11-2010, 08:43 PM

I have been having a really annoying squeal on and off for a few years behind my glove box on my 87 300d. Finally I got fed up with it today and tore out the problem. I think I read somewhere here a while back that it's some sort of feedback to the CCU unit. Maybe an ambient temp probe type thing.

All I know is that it became enough of a bother that I got it out. In the mean time I took it apart. It's just a small basic DC motor. I tapped it a few times and a bunch of little black particles came out of the motors vents. I fired it back up and no more squeal. But what is that thing. After re-installing I ended up uninstalling it. It was just hanging loose back there. Surely it doesn't just dangle free back in the dash behind the glove box does it?

Do the later W124s with the Passenger Air Bag still have this little thing?

emerydc8 · #2 03-11-2010, 09:22 PM

I think they call it an aspirator or temperature sensor ventilation blower. It draws air from the overhead panel near the rear view mirror for the temperature control system. Mine went out years ago. They're not too expensive from the dealer if I recall.

777funk · #3 03-11-2010, 10:21 PM

Quote:

Originally Posted by emerydc8

I think they call it an aspirator or temperature sensor ventilation blower. It draws air from the overhead panel near the rear view mirror for the temperature control system. Mine went out years ago. They're not too expensive from the dealer if I recall.

Ok I was under the impression that the CCU used a reading from that for something. I cleaned the motor out and put it back together. It seems to work perfect again. But I don't know where it mounts. It seemed to be hanging loose (maybe) behind the glove box. I'm not sure though. If I put it back in I want to get it back where it goes.

johnathan1 · #4 03-11-2010, 11:10 PM

I know in my W126, this sample motor was mounted to the right of the glove box...sorta behind the passenger vent.

emerydc8 · #5 03-11-2010, 11:16 PM

In my 400E, it was wrapped in some sort of foam-probably so it wouldn't move around. I don't think it was mounted to anything. Mine could be different because I had the passenger-side air bag.

compress ignite · #6 03-12-2010, 07:37 PM

The Aspirator Fan Motor sucks ("Negative Wind") Air from a tube that runs up the "A" pillar to the Temperature Sensor
[Little Slotted Plastic Square to the Left of the Front roof Cabin Light AND
just forward of the SunRoof Switch]

Without the CABIN air temperature Sensor information the CCU has no idea
how Hot or Cold the Interior of the Car is.

The test for the Fan Motor is to see if a 1" x1" square of paper is held up by
the Suction @ the square Sensor grid.

The Aspirator Fan Motor runs in all CCU push-button positions EXCEPT the one
on the farthest Right [Pictogram of Circle in a Square].

Picture of Cabin Air Temp. Sensor Intake below.

ds190 · #7 03-12-2010, 08:07 PM

Pull the glove box out and look around and under the large black plastic hose to the right dash vent. The aspirator motor is pressed into a foam mount as emery said, and that mount presses into a U shaped clip assembly near the right vent. It is the same for no air bag and air bag cars.

I also took apart and cleaned one, put it back in, and it's been working fine.