My fan clutch is not coming on like it should at high temps on my 85 190e and reviewing the archived posts on it I am a little confused now on its operation. I had originally thought that it is a purely mechanical device using viscous fluid to engage the clutch mechanism when the fluid got hot enough. Most of the archived posts on the problem seem to come from the fluid leaking out over time, but I did read about an electrical sensor that also triggers the fan to engage. First, is there a sensor that I can check on my 85 that might be the culprit or is that only on later models? What does it look like if so? Can I just short the posts together to engage and check the fan? Thanks in advance.

Steve