I have a Concord 80 plus HVAC unit. Model rgc80a100d12-3. Out of the blue the Furnace stopped working. Last year the port on the inducer was plugged. I have cleaned that off and that is not the problem this time. I have about 3 volts on that switch until the inducer starts then the furnace voltage goes to about 15. I have cleaned the flame sensor. Now what happens is the inducer starts then the furnace will click and the glow plug lights. Then the gas valve opens and the burners light. They are all blue and appear to be uniform. The furnace will run like this for up to and over a minute. Well into the time that the fan should come on. The furnace then clicks 2 separate times. Shortly after that the flames go off. The inducer continues to run for about 30 to 45 seconds and shuts off. The furnace will later try to start the process again. I tried turning on the AC and turning the temp down to 60 currently the temp is 62 in the house. The AC Condenser turned on outside and I could hear the fluid rolling through inside the furnace. The fan never came on. If I go to the thermostat and turn the fan "on" instead of "auto" the blower still won't come on. Doing the AC test there were no codes flashing. It was just Dim and Bright flashes. When the heat fails the light will flash 3 times.

It sounds like you have either a bad fan control or fan motor. Does the furnace have a circuit board to which the fan is wired?