At what point should the fan in my radiator start working? because i drove my car for about 30 min. as soon as i parked the car i popped my hood to check the fan and make sure it was working but its not, its a brand new radiator? could it be the temp. sensor maybe, it doeant seem like it would be cause the gauge in cluster works, my check engine light is not on. or does the fan spin while im driving. I need to know because my previous radiator craked and i dont want the same thing to happen to this one.