Engine temp sensor - how does it work?

[Stealer Of Souls]

Hey.
Can someone tell me how the standard engine temperature sensor works. I want to hook up a circuit to trigger my radiator fans and thought I might be able to piggyback off the engine temp sensor.

I'm pretty sure it's just a varying resistance, but would like to know a bit more detail.

Thanks.

[AceSniper]

the fans norm run off there own temp sensor/switch theres prolly more than one sensor.. one for the guage, ecu and fans

[Stealer Of Souls]

It's an AE85.5, fans are electric and didn't come with the car... There is no provisions for a sensor originally, they were belt driven.

[Malcolm]

Some sensors are switches and some are variable resistors. For instance the one running the gauge, the one that goes to an ecu, and the one that goes to the aircon ecu are usually all variable resistors, whereas the fan and cold start timer are usually switches. It would be easiest to just get the temp switch from another car and then drill and tap the coolant elbow or something similar and put it in there.

[matt dunn]

Hey.
Can someone tell me how the standard engine temperature sensor works. I want to hook up a circuit to trigger my radiator fans and thought I might be able to piggyback off the engine temp sensor.

I'm pretty sure it's just a varying resistance, but would like to know a bit more detail.

Thanks.

Yes they are varying resistance. You cannot hook them up to run fans.

What car do you have. If it's 4age rwd i have another thermostat outlet that has a switch in it that you can buy.

[Ae92typeX]

alternatly, I think it was jaycar who sold a temp sensor which can be hooked up to go at a chosen temp.

[Stealer Of Souls]

Hmmm, better be more specific methinks...

Okay here was the plan..
I'm assuming the temp sensor is basically a thermistor encased in metal housing which is then screwed into a water channel in the block. The idea was to tap into the and build a little schmitt trigger (comparator of sorts) which will drive an output relay to trigger the fans...

What I'm hoping someone will know is what the resistance varies from too for 20-100ish degrees C. So I can determine what the rest of my resistor values should be...

However, I've started to think this may be a little difficult due to the nature of things, so I'm thinking now I'll just go buy/steal a NTC thermistor and epoxy it to the radiator top tank...


I've looked at the Jaycar ones, and the kit I want isn't available yet, but I'm gonna investigate that when the stock arrives.