I bought a used set of dual radiator fans for my car, it did only have the one, but was told the two will work. I checked the motor first both fans work fine. when I plug it in and start the car, neither fan turns on. even with the a/c on. the car isn't over heating, its right in the middle. I let it idle in the driveway for about 10-15 minutes, and it didn't over heat. but I don't understand why there not turning on, at least the a/c fan. help please.