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

Fan clutch on that car should lock-up when the a/c pressure reaches 16BAR OR at 100C.

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190E 2.3 16V ITS SCCA race car (sold)
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Which 190E?
2.3 or 16v ?

If its a 2.3 then its an electro magnectic clutch that kicks in at 100C. Its basically a magnet that engages at that temperature. It is controlled by a switch at the top of the head. I believe it is a red switch.

Ok, then it seems that the red switch on the head should probably be the first thing to check. Can I either ground one of the switch posts or just bridge them to see if that is the problem? Thanks.