The fan should be resistant to spinning by hand to a certain degree.... more so when it is cold. The fan clutch is the aluminum hub between the water pump and the fan.
A shot fan clutch (which allows the fan to spin too freely), a clogged or restricted cooling system, a missing fan shroud or any combination thereof may cause overheating while the vehicle is sitting idle or moving at low speeds.
Do note that the MKIII's coolant sensor is logarithmic and that beyond the normal operation range the temp is either VERY cold or VERY hot... In other words, if the temp gauge presents a temp more than a couple millimeters from normal, you're quite likely running at damaging heat levels... shut the car down IMMEDIATELY!
__________________
If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum.
If you're so inclined I'm always more than happy to accept tips via PayPal. 
Tip Jar ---> 
|