Cooling fan cut-on temp.

[C411BRA]

just flushed the cooling system on my v6 in the week.

Now I have a problem with the main radiator fan coming on when the temp is only just above cold, even thismorning when the temp is -5deg.

Any ideas?

[C411BRA]

Its the main fan, dont have air. I filled it up til no bobbles came out of the bridge, sqished the pipes and so on, so it seems full.

I didnt disturb the sensor on the rad (i think thats the fan controller) so maybe its knackered.