Join Date: Sep 2006
Car: 2004 Facelift 75 Connoisseur 1.8 turbo with DD Pack. And remember, the troof is out there.
I'd say the slow speed in the fan motor has failed. The coolant sensor is probably OK from your readings. If the slow speed fails, the high speed will be tripped when the systems get to emergency state. For engine cooling, that's around 112C in the 1.8. The aircon system also needs slow speed cooling, but without that, the system overheats (due to lack of condensing function) and trips emergency cooling (high speed). This will cycle on and off every 30 seconds or so as the system overheats, then cools.
Since your car is a 2002 registration, it's probably got the original brush-controlled motor. The slow speed brushes have worn away. IF it has the later resistor-controlled motor, then the resistor has blown. Check behind the fan blades in the 2 o'clock position for the thin aluminium resistor unit. If itt's there, you're in luck (cheap fix). If not, you need a new motor.
The temperature gauge on the dash reads 'normal' across the range 75-115C. So not very useful.