That little fan motor, aka aspirator motor, is behind the passenger side air vent.

It sucks in air and blows it up the A pillar, through the headliner, and out through the vent that is right next to your dome light / sunroof control button.

The temp sensor for your a/c is up there, which registers the temp for your wheel, and also blower speed.

My mechanic replaced the one on my former W124. I watched him do it, and it looked like he inserted two thin plastic sticks into each side of the air vent, where they go into tabs. He pulled the tabs toward the middle, and the plastic vent pulled right out.

He could pull the aspirator motor right out so that we could see it and hear it run. Mine was noisy.

He simply unplugged it and installed a new one. Took all of 20 minutes.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".