Air Conditioning Pump??

I was driving along the freeway this last Saturday and I was almost to my destination. I had the defrosters going and everything was going good. All the sudden, I hear a loud pop noise then a hissing with like a whistle noise with it. Sounded like my tire popped!!! So, I pull over on the freeway and look at all the wheels.....Nothing, they were fine. So, I pop the hood next thinking maybe my belt snapped or a hose broke......nothing still. Nothings leaking and I can't find any broken hoses and belt is fine. So, I get in the Jeep and start it up and it runs perfect no noise nothing. Well a few hours later I was heading home and the windows began to fog up again, so I turn on my defrosters......here comes the noise again (without the loud pop). I turn off my defrosters, the noise goes away. So, I am assuming that it is my air conditioning pump that went out. Any suggestions?? Are these pretty easy to fix? They are kind of pricey I am finding out. Is there anything I can do to get me by without replacing the pump? I just don't want my belt to shred. Thanks in advance for the help!!

Fire it up and turn on the AC or the defroster , they both use the compressor. With the hood open try to locate the hissing sound and where it's coming from. Realistically AC is best left to a shop unless you have the device necessary to evac, draw a suction and refill the refrigerant..