i've got an electrical problem. . . i think

ok i stupidly let my sister drive my 93 si back and forth to work for a week or two. so the coolant was low and she failed to tell anyone and overheated the car and cracked the radiator so i recently bought a new one and installed it but the problem i am facing is that the fans successfully cut on before i installed the new radiator and now that i put the new radiator in they seem to cut on only when they want to i have a feeling that is an electrical problem but im not sure, if anyone has had the same problem or knows what i should do i would love the help

You do know that the fans are temperature controlled and turn on/off by themselves when the engine gets too hot, right?