If your thermostat is behaving erratically or something strange is in the display, hitting “Reset” buttons can often correct the problem.
Try this first since it does not erase anything. Take the front of the thermostat off the wall and look for a small round black reset buttons labeled “HW RST”. Hold this button down for at least 5 seconds and then let go. Again the screen should fully populate temporarily.
If this does not correct the problem, proceed to a Software Reset
This returns all the user-adjustable software settings back to their original factory default values when the unit was shipped.
This will erase your custom program settings, so write down all temperatures and start times before you begin.
To perform a Software Reset: Move the System Mode switch to the OFF position. Press and hold the UP, DOWN, and NEXT buttons all together for at least 5 seconds and let go. The LCD display screen will become fully populated and then return to normal.