I have changed out the control board on my furnace and had all the limit switched checked. My furnace starts upo like it suppost to but one the furnace gets to hot the limit switches kick in and shut it down. The blower never kicks on. Once the limit switches kick I get the flashing light that one or more of the limit switches are open. I have had the motor to the blower checked and it works fine. I'm guessing it is in the wiring from the control board to the fan or it's the relay on the board. Any other sugestions?

Does the motor even hum, or try to start turning? If so, I would check the capacitor. If it doesn't even attempt to run, check for power from the board to the motor when the motor should be running. If none, you have a bad board again.