The HVAC blower is in that area, perhaps the bearings are dry.

I've had the blower out of my 97 C280 , the description below might not be 100% but once you poke around there isn't anything difficult.

From under the dash, remove the "hush panel" , look up , there is a black cover held on with 2 white sliding clips, remove these clips and cover. Blower motor is screwed in from the bottom. Also. just to the left of the blower is the fresh air filter, probably a good time to change it anyway.

If you look up the instructions on how to change the fresh air filter, you will get to (I or near ) the blower motor.