The cooling fan will not come on and it is causing the vehicle to overheat. I have replaced the cooling fan, cooling fan relay, radiator is new. I also put a hot wire to the cooling fan to make sure that it is running and it works fine. I also checked to see if I was getting power from the relay and I have power from the relay. It has new coolant in it and the hoses are new. Please help, at wits end.