I recently had trouble with the Auxillary Fan on my 1991 190e 2.3 Sedan: The Aux. Fan was running all the time (it would kick in at 100C, consistently) and my main fan would not engage at any temperature(it is on a temp. controled clutch). The noise of the Aux. fan is what drew my attention to the problem.
Following the advice and wisdom of individuals from this forum, I replaced the 3 Prong Temp. switch which controls both the Aux. Fan and the main fan. The new switch corrected the problem with my main fan, however, the auxillary fan STILL runs from 100C and up. So, even though the main fan now engages when it is supposed to, the Aux. Fan still runs from 100C and up, whether the A/C is on or not. The Aux. fan is very, very loud and it sounds much like a lawn mower.
Do any other 190e Drivers experience this???