Tried A/C first time this year and it ran excellent. Turned A/C off and when I turned the key to kill the engine the truck wouldn't shut off. Idle rough and had the key out of the ignition. Did this for about a full minute before it shut off. Cranked truck up and everything was fine. Tried again a week later and this time the truck shut down normal. When I cranked it up, after getting fuel, the belt squealed really loud so I immediately tried to kill the engine and it wouldn't shut off. The belt was squealing loud and the engine was idling very rough, sounded like the started was turning over trying to start the truck. This went on for about a minute and a half, so I put the key back in the ignition and feathered the gas pedal and the truck eventually cranked up and I drove home. This hasn't happened again and I haven't tried the A/C since. I feel like the clutch is going out on the A/C, if so why would I have trouble killing the engine.