Radiator sensor ( electric fan.

[dickyb]

I removed my rad to have it rebuilt, But never took note of how the temp sensor on the rad was wired. The sensor has 3 lugs on it, I remember it only had 2 wires going to it. I take it that was power to it . and power to the fan but could be and no doubt I am wrong, The rad sensor is I think Rover. any ideas on the way it should be wired. Im Running the fan straight from ignition at the moment but I dont really want to do that. Thanks for any help, and from now on will take photos of any wiring.

[Happydaze]

I'd expect one contact goes to earth and the other goes to the switch side of a relay. Easy enough to check the continuity to earth with a multimeter, and ditto the relay, if you know where it is!

Chris

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[chevy2]

I have a 3 terminal rad switch,
its dual temp with only 2x wires that go to it,
the terminals facing each other have only one terminal connected and another goes on the remaining terminal to complete the curcuit when it reaches the temp to switch the fan on,
mines wired through the earth side of the fan but theres no reason why it can’t be via the live and then onto the fan supply,
you may need to swap terminals whilst running to determine which is the high/low temp side.

[dickyb]

Thanks Boys, The Fan has its own earth .So my way of thinking is one goes to to the middle and one to one of the others. much as chevy2 suggests.. Thanks to you both for your help.

[4_stroke]

Could be for a 2 speed fan. One pin common and the other 2 switch at different temps. Drop into hot water to see when they switch.

Power should be through a relay not direct to the fan.

[Happydaze]

I never considered a 2 speed fan, how very modern! Yeah, could / would earth through the switch, with the 2 wires going to separate relays or possibly a fancy, double acting relay maybe? Third connection on the switch might be an earth, possibly unused, depending on whether its necessary, eg no earth through the switch body when fitted to a plastic radiator end tank? So many options!

Chris

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[chevy2]

The hot option/cheap 2 speed fan in the US on muscle cars is from a Ford Taurus,
a friend used one on a Firebird,
that thing blew a lot more air than most aftermarket fans.