When I turn down the temp on the thermostat, the air conditioning unit outside comes on, but no cold air blows. When I turn it up, the furnace burners light for a few seconds but again, no blower and the burners go out. So it seems the a/c and furnace are working but there's an issue with the blower. Before I call a serviceperson - is there a reset button somewhere, or a simple fix I can try? It is an old furnace - Magic Chef circa approximately 1970.