Monovalve Going South ?
 

This morning I noticed a sudden change of climate in the car... CONSTANT HEAT ! First thing that comes to mind is the Monovalve - However I replaced those (have 2) about three years ago. Will they go bad so soon ?
car is a 1987 300SE Euro. Cooling system was flushed twice during that time!!! Once because it was time and once because the water pump had enough and quit on me.
As I am writing this another thought struck me..Maybe a FUSE ? Any thoughts would be appriciated. thanks