radiator (auxillary) fan

Here lately I've noticed that when I shut off the engine I can smell antifreeze. I've checked for leaks on the ground, and found none. I've also realized that the radiator fan doesnt come on as it usually does (note: I'm referred to the one attached to the radiator, and not the big one). Question(s):
1) Should I take it somewhere to have the radiator flushed to check for leaks? Can I place like Skill Lube, or Oil Change Express be trusted to do such a job?
2) What is the importance of the radiator (auxillary) fan?
Thanks
~BamaRodeo