Radiator Temperature Sensor: is it Knacked?

[SimonR]

MaestroMatt and I tried to get his car's cooling fan working today but even after I'd freed it off and tested it by bridging the temp sensor (it ran fine) we ran the engine until the overheating light came on on the dash but the fan stayed off.

I measured the resistance of the temp sensor in the rad and when the car was hot and it was either 450 or 850 M ohms (I can't remember as it was very cold and I was somewhat distracted). Anyway does anyone know what range of resistances should I expect to get from that sensor?

I suspect that either that or the wiring is knacked.

Cheers!

Simon R.

PS it seems from the fusebox that the radiator fan has no fuse - surely this cannot be the case?!

[Rich]

There should be voltage at the switch all the time, on one of the terminals if theres not theres a power issue to the fan switch. If when bridged with a piece of wire across the wires which connect to the switch the fan does not run and you know there is voltage there and the fan works then the switch is knackered! There pretty cheap, and easy to change.

It should just be either a closed or open circuit on the switch, I suspect your switch is seized and corroded up inside which would explain such a massive reading across it.

HTH Rich

[B18 GPC]

I cant say i heard "engine hot" today while it was on the MOT Ramp ;)

Congrats on the pass ;)

[B18 GPC]

assuming u mean the sensor on the rad itself...

unplug both wires.
unravel a paper clip
put in both wires.
if your fan comes on , then its your sensor.. :confused:

[Fast Guy]

MaestroMatt and I tried to get his car's cooling fan working today but even after I'd freed it off and tested it by bridging the temp sensor (it ran fine) we ran the engine until the overheating light came on on the dash but the fan stayed off.


What "it ran fine"? The fans? in which case fit a new switch.

If the fans come one as soon as you bridge the wiring connector that goes onto the switch, then it the switch that's faulty. If they don't come on then it's the fans or wiring. (can't remember if there's a fuse in this circuit:o )