IF it is like my car, should take about 20 minutes to change it.
Here is what it looks like ;
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1R510G7PR1T51A1I1B&year=1999&make=MB&model=CLK-430-001&category=R&part=Blower+Motor
The motor should be located just to the right of the cabinfilter, 5 screws holding it up.
http://w202cabindustfilter.homestead.com/
May as well change the filter too, while you're down there.

__________________
2007 C 230 Sport.