There is a little fan inside my dash, passenger side. Maybe there are more of them. Even with the HVAC off, it runs. Slow and barley audible.

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1991 560 SEL / 185k miles
1992 750il / 17k miles - project car

Colder weather in your area? It's the climate sampler motor. connects to a tube that goes to the little vent in the overhead light unit with the sunroof switch on it. It's what pulls air onto the sensor from the cabin for accurate automatic climate. Mine makes a clicky noise audible at start up; I assume you could unplug it and impede function minimally, but have no clue whether or not thats accurate.

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1987 560SEL (210,000 miles)

Guess that makes sense, but what an odd location for the fan relative to the tube. Although I suppose that tube does run down the passenger a-pillar.

Thanks.

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1991 560 SEL / 185k miles
1992 750il / 17k miles - project car

The tube runs from the motor through the A pillar to the overhead console. There is a small opening in the console...placing a small square of tissue paper there-it should stay- shows that it is working...

John

Don't try to spin the little fan backwards, it will damage the brushes.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

My sampler fan was barely turning. I removed it and pulled the motor out of the rubber molded pieces, and discovered that I was not the first to do this. Whoever worked on it just jammed it back together with no regard for wires getting pinched, etc.

I cleaned it up... the fan was full of clods of dust and hair, and put a drop of oil on the bearing. Now, it spins fast, and silently. Put it back in the car, and the climate control is much better. There are no big swings in temperature in the car anymore.

This was almost 3 years ago. It's running fine, and I found an almost new replacement to use if this one ever fails. So far, so good.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.