Yes
Behind driver headlamp area ..check for poor connections at terminals
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1D00YU6RY1JL0RQTFV&year=1990&make=MB&model=300-SL-001&category=G&part=Aux.+Fan+Resistor

archieves -fan resistor