On my 2.0TS, that's where the fan kicks in - but it stays on until it's reduced the temp down to the 90deg mark.
Not sure why yours doesn't ... could possibly be a fault in fan relay (if it's clicking open-circuit again), or in the fan itself. To rule the relay out you'd first need to find it (there's a variety of locations depending on year and model) and then keep a hawk-eye on it as it switches the fan on. If the relay's behaving OK, then I'd try changing the fan.
If the relay is clicking open circuit again, you'd need to work out if the switching current had dropped (telling the relay to switch open) or if it was the relay itself at fault.
If the relay's fine and it's just being told to switch open, then you'll need to work out how it's controlled. Earlier models had a temperature sensor on the rad near the bottom hose - these can fail. Later models are driven from the ECU, using the temperature sensor on the thermostat.