Re: Furnace Thermostat
Reply #4 –
There should be a pigtail that plugs into the side of the furnace which should have a red a black and 2 blue wires. The red is for 12 volts + and the black 12 volts- and the blue to the thermostat. One of the blue will have 12 volts positive and the other carries the 12 volts back to the furnace to activate the furnace. There is a time delay before the fan comes on and then the circuit board has a delay before ignition.