1986 Mercedes Benz 300e Auxiliary Fan Cooling Sensor

Ive looked for that sensor the only thing popping up is the AC fan pre-resistor and aux fan relay for the high and low they all in the main fuse/relay panel

The sensor is on top of the cylinder head, it has three leads, others have only one or two points. It is the hot water termperature sensor. The Aux. fan senses the engine temperature from that sensor, and accordingly it engages whenever it needs to (when the engine heats up to about 110 C, e.g., when the air condition is on). If that termperature sensor is falty, the aux. fan will not go or it will go nonstop, even if the engine is cold. I hope this helps.