THERMOSTAT BLANK or THERMOSTAT DOESN’T WORK– The display on a digital thermostat shows no information or the thermostat does not function properly.
POSSIBLE PROBLEM & DESCRIPTION
Most digital thermostats require batteries. Try replacing the thermostat batteries and see if the display returns. Watch Video.
Loss of Power to the Furnace
Low voltage power for the thermostat and controls comes from the furnace. Make sure there is high voltage power to the furnace. Make sure breakers and any service disconnects are turned on.
Most newer furnaces are equipped with a blower door safety switch the "kills" power when the blower door is removed. Make sure the blower door is securely in place.
No display may just be caused by a bad thermostat. If there are good batteries and the thermostat is receiving power from the furnace or air handler, but there is still no display – it is likely a bad thermostat.