Yes, it could have been on a LOW FEED RATE and the fans would have been at MIN or too low a voltage to actually run. If you plugged a Regular fan into the Same Convection Fan Outlet on the CoalTrol, It would do the same thing, since the Fan Speed is based on Feed Rate. The lower the stove setting, the slower the blower speed.
Can you UNPLUG the fan and plug it Directly INTO an OUTLET. That will determine if the fan is good or not. If it goes up to FULL SPEED, nothing is wrong.
You would need to change the MIN CFT setting (Convection fan Threshold) to a higher number so the blower doesn't just sit there.
You can TAP the Menu button and goto FSA (Fan Speed Auto), and push the UP or Down Arrow to set the fan speed to see if it works this way. It will change to FSM (Fan Speed MANUAL) and a number 1-99%, You have to put it back to Zero (0) to put it in AUTO Mode (FSA).
In the Advanced Menu (Hold the SETUP for like 15 seconds) I believe is the CFT setting that you would have to raise to like 30 or 40, I think?