BMW Repair: BMW Radiator and Auxilliary fan Not coming on, upper radiator hose, radiator cap

Question
I have a 1999 bmw 323i that the fan one day just went out.  It comes on when it feels like it.  Due to this problem I now have a cracked radiator.  Also, when the temperature goes up, the AC seems to just stop working.  What is this problem?  I am thinking about taking it in to a radiator/AC specialist.  Will they know where to locate the fan switch, relays etc?  Or can you help me locate them?  Please help.  Thanks!

Answer
Derrick, replace the fan, common failure item, the relay is on the fan assembly itself and can't be replaced separately. It is more like a transistorized module really.
If you over heated the motor enough to crack the radiator replace the thermostat and radiator cap. Sometimes the upper radiator hose O-ring won't reseal after being over heated so I would replace it too.
-Evan