I'm a relatively new homeowner. In the past, when I programmed the thermostat to a particular temperature at a time, the A/C would come on at that time if the current temp was above the programmed temp. But in the new house, the A/C would come on several hours ahead of the programmed schedule. I resorted to turning the entire unit off when I left the house in the morning to keep it from running when no one was home. After doing some research, I realize that there's a computer that is trying to anticipate the time/temperature I set. But I didn't want the A/C to run for hours before it was scheduled - I wanted it to start running when it was programmed to. This would be nice technology if energy were free but instead it's a major hassle and probably part of the reason my electric bills were so high. Why should the A/C start running at 7 if I'm not going to bed until 10?
So, I found out how to disable this stupid "feature." Guess the thermostat wasn't so smart after all.