This is how I solved the same problem on my 94 E320. Remove the air vent on the passenger side. Remove the cover under the dash using a socket (10mm?) on a 6 inch extension. Now you have access for each hand - left hand from below and right hand through the open vent. Pull the air sampler motor/fan (enclosed in foam insulation) up and out through the vent; once removed you will see it is held in place by two flat spring clips. Disconnect the electrical harness, and remove the motor/fan from the foam insulation. Repalcement is the reverse of removal. Total job should be less than an hour.
regards,
Mark