Coolant sensor. Help.

[ColbsE30]

Which sensor is the sensor that tells the auxiliary fan to turn on? I have a new aux fan but it never seems to turn on. So if anyone knows which one it is or where I can get one please let me know.

[mpowerful]

The sensor might not be the issue. Checj out aux fan troubleshooting. Google that for an e30. Youll find the poat with a long list of steps to figure out why it isnt coming on.

[TSI]

It's the one plugged into the right side of your radiator, however the fan resistor is notorious for crapping out. Try jumping the sensor, if the fan spins then your sensor is bad. If it doesn't, you have a fan problem.

[ColbsE30]

It's the one plugged into the right side of your radiator, however the fan resistor is notorious for crapping out. Try jumping the sensor, if the fan spins then your sensor is bad. If it doesn't, you have a fan problem.

What do you mean by jump the sensor? And it's basically a brand new fan. I'm having some trouble figuring out how to check if it's the resistor also.

[TSI]

What do you mean by jump the sensor? And it's basically a brand new fan. I'm having some trouble figuring out how to check if it's the resistor also.

There are three terminals. One is ground, the other two are thermally-activated circuits. The circuit closes when the temperature reaches a certain point. When it goes higher, a second circuit closes to give the fan max power. It's a two-speed fan.

[vpilarrt]

Unplug the harness from the fan sensor on the right upper end of the radiator. With the ignition key in the "ON" position 1 of the 3 contacts in the plug should have +12V. With a piece of wire connect it to 1 of the other contacts (with key still on). The fan should run at either low or high speed. With the wire connected to the other contact the fan should run at the other speed. If you never get low speed the resistor may be bad or you could have a bad relay or a wire break somewhere.