@fusebox. sounds like a bad thermoswitch. Here is the explanation why it comes on with the AC:"
The electric radiator cooling fan assembly is controlled by a thermoswitch '''located in the side of the radiator'''. At higher coolant temperatures, the switch closes to start the cooling fans. Any time the coolant temperature rises to higher than normal levels, the fan will start and continue to run until coolant temperature returns to a normal range. On vehicles with air conditioning, '''rising refrigerant pressures will also activate the cooling fans.'''
Attached documents will show you how to test the switch etc. [document|4751]