I have a 2010 GMC Sierra 4.3l v6. Wt 4x4. I have seen my problem on other forums. With no confident solutions. The engine hot turn ac off displays on odometer and temp drops to zero. It happens a few times a week within a 1/4 mile of the same spot. I know the engine isn't hot because it's still on when I get out of work. Seems when temps are cool in the morning.