| As mentioned different STs have different systems, if its a ST3 with a 5.9M ECU it will be controlled by a Negative Temperature Coefecient (NTC) sensor that once its resistance reaches a given value the ECU turns on the fan,
For an ST2 with a 1.6M ECU the Fan is probably controlled by a themostatic switch.
Removing the 2-pin connector from the switch and shorting out the two connector pins with the ignition ON should make the fan come on, if it doesn't then either the fan is faulty or a relay or fuse has gone.
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