engine temp vs. ACC sensor
 

1993 190E 2.6 M103 engine

I have a sensor between the air cleaner box and valve cover on the driver's side, looks like a blue two-connector. Which is this? Also, where would the green 3-prong engine temp sensor be located? I need to stop the aux fans from spinning on high intermittently, and have been advised these may be culprits. Any advice on using a voltmeter to troubleshoot these? I'd rather see if they are bad before replacing them. I have a voltmeter, but wouldn't know what to set the selector to or what values to consider when testing these sensors. Thanks

Aux fan sensor on that car is a blue 2 pole sensor

alright, thanks - so where is the green 3-pole sensor located? Can't find it

As MB-Doc stated, that is the Aux Fan sensor.

Culprit?? If the A/Fans spin, high or otherwise, it's b/c they NEED TO! There's nothing wrong. Menu#18 shows how the sensor works w/ the A/C and Aux Fans.

Thanks Jim but as I stated it's an intermittent on/off when the engine temp is normal, as if somebody is getting their jollies flipping a switch on and off. Definitely not normal. Now - where is that green 3-prong engine temp sensor located again?

Is the A/C on? If so, then it's normal since a burst of high pressure causes the second part of the ckt electronics (pressure switch on the rcvr-dryer) to turn the aux fan on to cool the evaporator even though engine temp is normal.

My 190E did that alot!

My aux fans would go on and off randomly, normal temp, no A/C. I replaced the blue/two-prong sensor and it all works fine now. I don't have a three-prong sensor on my 91 2.6. Can't help you there.

That's what mine does - so I guess testing would be a waste of time. I'll just get a new one.