1998 Jeep Cherokee Electric fans stays on for hours

Engine Cooling problem
1998 Jeep Cherokee 6 cyl Four Wheel Drive Automatic 111k miles

My electric fan stays on for hrs to the point that it can drain my battery. A first it used to stay on for a few minutes after I turned off the car, now it stays on for hrs after I turn off the car. The only way to stop it is by unplugin it from the connector that comes from the wad of wires. When I leave work some 9hrs later and plug it back on it continues to run as if a switch was left on for all those hrs. Please help me zero in what it could be causing this. Thank you