Are you referring to a ULS engine with a Dynon Skyview installation? If so, as i recall the two fans located on the avionics platform are on the same fuse circuit as the electric fuel pump. Does your electric fuel pump operate when the Master is ON? If not, then verify that the fuel pump fuse is functional.
Also there are also two small fans on the back of the Skyview display that operate whenever the Skyview unit is ON and calls for cooling (they are equipped with thermostats).