Wilsop, one thing to check is whether the fan resistor has gone open circuit. When this happens the coolant temp clicks the fan in at full speed once the temp has reached 92-95C.
The first speed is slower and kicks in at around 88C.
The resistor is located at the top on the fan assy (Remove the large connector first) and held in by one small bolt.
Using a multimeter, measure the resistance between the connectors to check its around 1 ohm. If its open circuit then the item is faulty.
My one had the resistor unsoldered one end, which I managed to repair.
You can check both the fan speeds work using FIAT ECUScan diagnostic software too if you don't have a multimeter.