| You COULD call, or I could just tell you that is what they call "Auto Recovery Mode" It has to do with the energy savings feature and will happen when there is a scheduled change in temperature that will require the furnace/air conditioner to kick on. It's just trying to change the temperature gradually before the start of the next program period to keep it from having to work harder and cost you more money. If you pull it off the wall and turn it over you can disable the "Auto Recovery" switch (SW4) and it will no longer do it. Leaving it on won't hurt anything but it may save you a few extra dollars every month. | 
Linear Mode
