Auxiliary Fan (Compression Shroud) DIY [Air Conditioning]

[urcbmw8]

Hello there,
I have 2001 X5 4.4i and I just had my radiator replaced because it broke and I still smell kind of burning coolant. However, I am wondering about the aux fan outside sitting in front of Radiator, does this fan suppose to turn or blow all the time or just when it gets hot. Does this aux fan help to cool radiator or this fan is just for A/C? The main fan inside works fine every time I turn on the engine. I just concern about the aux fan outside, does this fan have anything to do with Radiator? Why my radiator broke? Is it normal when you reach 150,000 miles. Please advise.