When I bought my 2000 Sport about four months ago, every time I would turn on the AC I would hear a noise from under the hood and my rpms would drop slightly while I was driving; It technically worked though as it was blowing cold air. After awhile however it started blowing hot air so I avoided using it; up until yesterday when I put about a pound and a half of refrigerant in it to make it cold again. It was working fine and I was running it on full blast for most of the day yesterday. While I was driving last night however I heard a similar noise to the noise I heard when running my AC for the first time, my steering went completely stiff, I had a check gauges light come on, and the thermometer read the engine at 260 degrees. Luckily I only had to drive it another 200 feet or so until I could pull off the road. When I popped the hood I found my belt completely tied in a knot and I was dripping coolant from the bottom (I'm guessing as a result of the engine overheating creating too much pressure in the cooling system). When I got it back home I found the belt completely intact, but my water pump was completely seized. I realigned the belt and tried to start it but the belt just slipped off again,
I know I have to replace the water pump at this point but my question is, do I need to replace my AC compressor too? I never had any problems with my jeep until this point, coincidently the same day I started really running my AC. I think something went wrong with the compressor causing the belt to slip, simultaneously messing up my water pump; I may be wrong though. I don't want to keep replacing water pumps if the compressor is the root of my problems.

 

No. Put a water pump on it and hopefully you didn't overheat the engine too bad to require a head gasket. Change the thermostat while you're there.