so , i blow my head gasket, all the reparation have been done on the head before the assembly of the motors. but now my cooling fan wont start anymore. i have tcheck all the fuse in the fuse box in the car and under the hood, everything fine. my ps fan works great. i have change the relay in the fuse box and they all seem to be fine. but when i plug a batterie pack on the fan, the fan start. so i dont know where to look??