What control's the radiator fan to come on? Seems like my radiator fan is not turning on making my temp gauge rise then fall back down,just did my coolant flush,thermostat,coolant temp switch also

 

Fan switch sensor.. On thermostat housing

 

First of all, check for the fuse in the under-hood fusebox.

If that's ok, unplug the temp switch right above where the thermostat and bottom radiator hose meet. Then with the key at ON position (without starting the engine) short the two pins from that relay using anything conductive. Screw driver or wire. See if the fan turns on.

If that doesn't work, check for the voltage across the lead where the fan is connected while the relay is still being shorted.