I'm trying to run the fan on my furnace and it's not working. The heat and AC work fine and the fan turns on with those options, but not when I simply turn the fan on. I jumpered the G and R wires at the thermostat, but still nothing. Then I jumpered the G and R on the control board and there is a click. I'm assuming this is a relay. The fan still doesn't start. I had the whole control board replaced about a year ago, but never tried the fan on its own. The furnace is a Lennox about 13 years old. The control board has a flashing red and flashing green light. Both are flashing at the same time. Not sure if this is normal or indicates a fault. Any insight on what is going on?