Rad fan doesnt start when the engine is hot, but when it's cold?

[WidowmakerS2]

Odd problem that has occurred lately.

When I start her up cold, the fan starts for 2-3 seconds like always, and i can start it by pressing the "off" or "ECON" button on the ac headunit.

However, it doesn't start when the coolant gets warm, OR if i stop the car and turn on the ignition again Resistor/heat problem maybe?

[martinws]

Does it work by shorting wires at the temp sensor on bottom of rad?

[Error404]

When I start her up cold, the fan starts for 2-3 seconds like always, and i can start it by pressing the "off" or "ECON" button on the ac headunit.

None of that sounds right!

The fan should only run when the AC is on (in fan speed 1, or speed 2 if the high pressure switch is active), or when the rad fan switch (in the bottom of the rad) triggers it. (speed 2 and 3).

It shouldn't come on when you start the car and shouldn't come on when you switch off the AC!

you can test speed 1 by connecting the afterrun pump terminals
you can test speed 2 and 3 from the rad fan switch with a piece of wire etc

[WidowmakerS2]

Hmm, the fan doesnt start, but it does 'blip' on when the ignition gets turned on. I've been told this is normal

The fan is wired in by me, but that does not have anything to do with the AC bit. I've only replaced a 300W fan with a 500W, using the resistor plate i bought on here, and two relays. All my wiring is in the engine bay..

[RS2 driver]

I have a kind of similar problem/issue with my RS2 rad fan.

When the climate panel is on and the digital cabin temperature is adjusted above 19 deg C. the fan starts running no matter whether the A/C is on or off, and independent of engine temperature. It will keep running until adjusting temperature below 18 deg C. which causes the fan to stop again.
If the temperature setting is below 18 deg. C. or if the climate panel is turned off, the fan will start at engine temperature of approx. 92 deg C. and run for a while before stopping. Just as it should.

Have anyone experienced similar behavior?

[WidowmakerS2]

We don't have the same climate control unit, but it seems like the problem could be similar.

I'm looking towards wiring up the radiator fan without any connection to the climate control, as i no longer have the AC.
There seems to be some electrical fault doing this with mine, as it sometimes work and sometimes don't.

I'm not sure, as I haven't got the wiring scheme in front of me, but I think I only need the earth wire and two relays to make it work.