I have a Goodman gas furnace that won't start on it's own. I can hear the thermostat click but nothing happens to the furnace. If I cycle the emergency cut off switch while the thermostat is on, the furnace will start and run normally until the room reaches temperature. However, once the temperature drops back down the furnace still won't restart. Anyone have any ideas about this one? I don't work in HVAC, but I do work in a technical field so the more detail the better. Thanks a bunch in advance!