I went an extra step to find the info for you. Below attached are instructions with pictures. Yours is a W210 I assume.

However I think you problem is beyond the filter. It seems the drainage is blocked and a pool of water stayed inside the system to breed germs etc. You ma want to make sure the drainage holes aren't block.

You can also run full heating with windows open, EC on and recirc on for about 15 minutes. I was told that this step will heat up the system to kill the germs.... I was also told that in future, the last 5 minutes before shutting down the engine, put EC on so the FAN will dry up the evaperator..

hoppe this help. Keep us posted!

Sorry cannot upload due to size. you got an email?