Kia Sportage cooling fan

I have a 2002 Kia Sportage. The cooling fan does not turn on by itself, but I have noticed that it does go on if I turn on the air conditioner. What can my problem be?

The fan is controlled by the heat it believes is in the radiator.  That sensor may be out.  Turning on the A/C bypasses the thermostat control.  I would look for the temperature sensor for the radiator fan.

BTW does it have one or two fans on the radiator?

You say the fan won’t come on by itself, but is the vehicle overheating? Does the temp gauge go higher than normal at all?