You can test the cooling fan system,the gregorys workshop manual says-
Check that the fan does not rotate when the engine is cold and the ignition switch is in the on position.
Connect a jumper wire between terminals A and B on the diagnostic connector under the glovebox.
If the cooling fan now runs,this shows that the cooling fan and its associated components are all working satisfactory.
If the cooling fan runs when the engine is cold,remove the cooling fan relay from the fuse box under the bonnet,and check for continuity between the relay terminals 30 and 87 using an ohmmeter.If continuity is present renew the relay.
If continuity is not present,proceed as follows,
A)switch the ignition off,disconnect the control unit wiring(ECU connector) and check for continuity between the relay connector terminal 85 and earth using an ohmmeter.
B)If continuity is present,rectify short to earth.
C)If continuity is not present,renew the control unit (ECU).
On air conditioned models a further check is possible.Remove the jumper from the dianostic connector.Start the engine and let it idle.Switch the A/C on,and ensure that the cooling fan runs.
If the fan does not run,check the cooling fan relay.
Id say that seeing your fan comes on with the A/C, the cooling fan system is working fine.Id replace the coolant temperature sensor.