Originally Posted by aTOMic

Emilio,
You can try to clean it; it sucks up a lot of dust and can get noisy. Remove the dome light ass'y by prying it down from the rear edge. (the aspirator fan/temp sensor unit is behind the little slots on the passenger sideon the W210). I blew mine out with compressed air it got a little better but I replaced it because it annoyed me. Call Phil at Partsshop he will know what you're in need of. It plugs in and snaps on, easy 20 minute job and it will be completely silent.

Do a search on the words aspirator, cabin temp sensor, or sampler and put your car's body style (e.g. W210 for mine) for more info.

-Tom