How does it know?

How does my downstairs air conditioner know that it is the Friday of a holiday weekend? Or that it is a friday at all??? This inanimate object with no brain seems to know when to crash. It is currently 81 degrees downstairs and 77 in the gameroom upstairs. It is comfortable in the upstairs bedrooms because the upstairs unit is working fine (actually, it is working overtime to cool the upstairs becuase the thermostat is in the game room) but the down stairs is not comfortable. We have the fans blowing in every room, kicking up dust from far corners. And it is Friday, of a holiday weekend. Luckily, we have a friend. One who will be here at 9am tomorrow and is HVAC certified. Hopefully he can fix it until Tuesday...when we call the warranty company and pressure them to replace the unit. They come visit us at least once every 2 months. And it is almost always on a weekend!!! They have already replaced our upstairs furnace and upstairs coil in the air conditioner. The next logical thing would be to replace the downstairs unit. It is 20 something years old afterall!! No one ever said warranty companies were logical!!