I posted in this recent thread where Compress Ignite showed pics of a W124 dirty coil and how to clean.. check it out.
http://www.peachparts.com/shopforum/showthread.php?t=258481
The blower and the dirty side of the coil is accessed under the hood under the wiper assembly not from the dash on a w124 so dont go that way..I also dont recommend any brush to prevent damage. Mine was badly impacted and built up so you could not even see fins and 80 psi of compressed air at an angle blew the dry debris out of the fins before using the foaming cleaner.
I found instruction for blower removal here on the wiki it is for a coupe and gasser but is the same for diesel W124:
http://www.peachparts.com/Wikka/W124BlowerMotor
Hope this Helps
Arlo