I was wondering on abjbrtd post showing his digital thermostat If they took a voltage reading with the furnace not calling for heat the left green wire says 12volt the middle red wire look's like comm and the right side is white and says 12volt. If a reading with nothing running was reading 0 volts and if the fan was manually turned on it might read 12 volts on the white or green. Then start the furnace and it should send voltage to the furnace on the white or green. When the furnace calls for heat and it fails if there is voltage on the lead to the furnace that makes it run, I would think something at the furnace isn't working. If there isn't power like before when the furnace was running the thermostat is malfunctioning
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