Jeep Repair: 95 G. Cherokee Whine with A/C on, pulley, screwdriver

Question
Hi, my mom owns a `95 Jeep GC and every time you turn it on and turn on the A/C it will start to make a whinning noise. When we press the A/C switch to the off position it will stop doing it. Any advise on why it does it and how could we stop it. Appreciate your help Doug.  

Answer
Well, based on the description it sounds like the a/c compressor is starting to fail internally.  Popping the hood and feeling the compressor or using a long screwdriver as a stethescope (sp?) may help prove this.  There's also the possibility that you have a pulley going out and when the a/c is turned on you increase the load enough to make the noise more audible.
Doug