The xxxxx310 is the aux fan sw. The other is system pressure sw.

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2FG17RJ3A2GH0VFWLU&yearid=1992%40%401992&makeid=MB%40%40MB%40%40X&modelid=300%2DE%2D002%40%40300E&catid=R%40%40Climate+Control&mode=PA&subcatid=R1055@@A%2FC+Temp%2E+Switch&source=www.peachparts.com&clientid=catalog.mercedesshop

What makes you think the sw. is bad? That switch is one of the most commonly mis-diagnosed switches.

__________________
A Dalton