when my xon turns off his 2006 chevy colbalt it sounds like the fans stays on about 3 mins

That sounds like the normal cooling process to me. As long as it operates at around 185 all is well. When you park, heat trapped under the hood and the lack of circulation at the sensor will cause the temperature to spike and the fans are designed to run for as long as it takes ti dissipate that heat. When the car is cold check the coolant level just to be sure. If it is I'd say all is well.