my circuit board on the furnace has no lights on, it has 12 volts on red wire going to it. Blower fan does nothing when setting thermostat. Board was replaced about one month ago first time trying since it was replaced, worked when tech left.
If the red wire actually going to the board has 12 VDC and no blown fuse on the board then likely a board or connection issue. Make sure the 12 VDC is making it past the Reset/ON/OFF switch and you have 12 VDC going to the thermostat. Test by trying to run the Air Conditioner.