Cooling fan trigger

[SparkySparks]

Hi all
What is the cooling fan trigger in these cars.
I have got it going straight to the battery atm so its permenantly on.
Im about to start cutting up the loom and I understand that the aircon has a part to play in it.
I gather its the large flat type 2 pin plug down by the fan that is the actual live and trigger but what tells the ecu go, is it the temp sensor?
TIA
Mark

 

[bloke]

Coolant temp sensor and the resistor is for the twin speed for the aircon.

 

[SparkySparks]

So the coolant temp sensor is showing its heating up, does it get to a certain temp and tell the ecu.
If I'm cutting out air con wiring will there a be a live to the fan from there?