It could be two things. They may be referring to the high limit switch would be mounted on the front wall of the furnace and have two wires attached to it. Or they may mean the motor's thermal overload but typically the motor's internal overload is not sensed by the circuit board.
I'm going to see if I can get the service manual on it.
I'll be back in a few minutes
I can't find a mnaual on it. Do you have yours ?
If you could give me the manual number it will help.