If your thermostat is set to auto heat why aren't the blowers running if the burners come on but the auto cool air works fine?

In some ac systems the blowers wont come on if only a slight tempture change is needed, or ther could be a problem in the wiring and the blowers are cut out of the heating loop It could also be that the fan limit is not working properly. Do the burners shut down after a few minutes of heating?