The Climate Control unit is right behind the center dash controls for your A/C-Heat System. I would have your Climate Control System scanned to see why the fan is going on and then off. Look for the fan 'on' data point in the data stream. If the Climate Control Computer is commanding the fan 'on' and it is not coming on, then it could be the fan speed module.There is often a separate module that runs the fan at varied speeds and they can go out, much like a Blower Motor resistor pack in a simpler A/C-Heater System. Good Luck!