Jaguar cooling system noise

Just purchased a 2004 jaguar xj8 w 60k miles from a reputable dealer. Love the car. Runs well. Only issue is I have is a hum or whine when the air conditioning system is on. If I turn off AC I still get noise. If I turn off climate system totally noise goes away. Seems to me to be the fan and not the compressor. Noise increases or decreases based on engine revving. Any ideas as to what to do. All systems seem to be working fine. Thanks