Radiator upper sensor disconnected

[E3IS0]

Hello everyone, This sensor has been disconnected for a while now and I am trying to fix it. Does anyone know what this sensor do? Does it relate to the fan speed in any way?

[Northern]

It's the switch for the aux fan (the electric one in front of the rad)

[D3R3K]

Its the dual temp switch, turns on the aux fan when the temp up, and can turn the fan on low or high speed. is your car a early or late model, they changed the wiring when the late model came out and the switch

[E3IS0]

Its the dual temp switch, turns on the aux fan when the temp up, and can turn the fan on low or high speed. is your car a early or late model, they changed the wiring when the late model came out and the switch

Thanks for the info guys. Mine is a late model 1990. Should i just connect the 3 wires and see what happens?

[e30strokr]

you definitely should hook up those wires correctly... this keeps the car from overheating when driving around town....

[IceWhite]

you definitely should hook up those wires correctly... this keeps the car from overheating when driving around town....

Then, what does the fan clutch do, or what is the purpose of the fan clutch?

[roguetoaster]

Then, what does the fan clutch do, or what is the purpose of the fan clutch?

The clutch on the fan is designed to make the fan more effective as the viscous coupling heats up, and less when cold.

[E3IS0]

you definitely should hook up those wires correctly... this keeps the car from overheating when driving around town....

Yes, I have noticed the heat creeps up when I am driving in town with it being 100 degrees outside. But it goes back normal when I am on the highway. Is there a diagram or something like that that shows which wire goes where?

[IceWhite]

The clutch on the fan is designed to make the fan more effective as the viscous coupling heats up, and less when cold.

I understand the purpose of the clutch in the fan clutch, but, maybe I should have been more specific. If the aux fan keeps the car from overheating, then why is the fan and it's clutch also a part of the system? What is it's purpose?

[E3IS0]

I understand the purpose of the clutch in the fan clutch, but, maybe I should have been more specific. If the aux fan keeps the car from overheating, then why is the fan and it's clutch also a part of the system? What is it's purpose?

I think they both have the same purpose. So when the clutch fan cant keep the temp down by itself, the aux fan turns on to help cool the engine down and turns off when the temp desired has been reached.

[D3R3K]

I think they both have the same purpose. So when the clutch fan cant keep the temp down by itself, the aux fan turns on to help cool the engine down and turns off when the temp desired has been reached.

Correct

wiring diagrams here

http://www.armchair.mb.ca/~dave/BMW/e30/