scavenger fan sensor

[mikexgough]

Hi
I test the scavenger fan every spring. First pull the connector off the sensor and short the connector...fan works. Next, connect it back up and play a salon type hairdryer on the sensor...when its hot ...fan works. It rarely switches on, and it only kicks in here after the car has been parked for 10 minutes in summer when the air temp is around the mid 40s plus. If you leave the car parked for 20 mins/ 1/2 hour, the engine cools a bit, heat is lost from the engine compartment , and it won't kick in.
The answer...you're unlikely to hear it, because it hardly ever works
Cheers
Helen

I agree....... the test once a year is a a well worth check........ and again I second the comment about how little it operates....
Worth a check to see if all is well before wasting money on bits n bobs you don't need...

[dandywarhol]

Well that's usefull, because bongobits.com want £80 for the sensor when you can get them for £16.99 from ignitioncarparts.co.uk

I'm not paying £60 for a small bit of plastic when I dont even know whether my current one is faulty or not...

Good find - also makes sense - both measure air temperature. BUT, if it is the same switch..........it also means that the engine bay sensor isn't a simple on/off switch (something I've been bleating about for a while now ) - its giving a signal to the ECU of a varying signal for the ECU to decide when the auxiliary fan cuts in. Thats why people get different results when disconnecting/flashing the sensor over a variety of ambient temperature ranges. The auxiliary sensor swich works in conjunction with the coolant sensor according to what I can make out in the manual - and why I don't go down the route of bypassing it to manually switch it on............................................

[mikexgough]

. BUT, if it is the same switch..........it also means that the engine bay sensor isn't a simple on/off switch (something I've been bleating about for a while now ) - its giving a signal to the ECU of a varying signal for the ECU to decide when the auxiliary fan cuts in. Thats why people get different results when disconnecting/flashing the sensor over a variety of ambient temperature ranges. The auxiliary sensor swich works in conjunction with the coolant sensor according to what I can make out in the manual - and why I don't go down the route of bypassing it to manually switch it on............................................

Exactly my thoughts.... ..... we shall find out the absolute on that theory when the ECU work has been done...... if it comes out how I think it will ................ it will put to bed the need to bypass or to install any device or switch to override the ECU and switch on the fans

[Rhinoman]

Good find - also makes sense - both measure air temperature. BUT, if it is the same switch..........it also means that the engine bay sensor isn't a simple on/off switch (something I've been bleating about for a while now ) - its giving a signal to the ECU of a varying signal for the ECU to decide when the auxiliary fan cuts in.

We should be able to tell from the schematic if its a thermo switch or a thermistor.