After fishing around on YouTube for useful ideas to narrow down the cause of my over heating issue I'm wondering if it's the fan.
After starting engine if I switch on the AC should the fan start up immediately? Mine doesn't.
With AC on the fan should run at low speed continually. With bursts of high speed fan. It is really obvious the fan is running high speed, makes a lot of noise and you can really hear it - not when driving along obviously, but when idling or in traffic.
When driving/running with AC off, the high speed fan should cut in at about 108-112°C. If you are stop/start driving in town traffic, hot day, window open, you cannot miss it coming on. Incidentally, the thermostat opens at about 90°C.
The temp gauge is only really a rough guide to what is going on - accurate within maybe 20-25°C. If you want to see the actual temp try the process below and watch. It won't solve the problem but may help you with the diagnosis. Display Actual Coolant Temp R50 Cooper and R53 Cooper S Hatchbacks 2002-2006
R52 Cooper and Cooper S Convertibles 2005-2008
1. With the key in the ignition, but in the off position, press and hold down the odometer reset button with one hand.
2. While holding the button down, switch the key in the ignition to position 1 (first click) with the other hand. The screen will have a number and the word “TEST”.
3. Scroll through the numbers by pressing the odometer rest button, through to 19 and wait a moment. (Note: the number order is: 1, 2, 10, 19)
4. The message will say 19 "L i-off", flash to "L i-on", and back to "L i-off" again. When "log i-off" appears, press the odometer rest button again.
5. You are now in the system.
6. Scroll through to 7.0 Actual coolant temp.
7. Start the engine and actual temp is displayed and you will see the temp fluctuation as the thermostat opens and closes.