I have this model(Bryan CB5AXA030000AAA) and the heat will come on for just a few minutes and turn off. I have replace the thermostat and still it will not heater will not stay on. The Blower seems to work. Help!

The model # you are giving looks like the # to the evaporator coil. The model # for your furnace is inside the furnace left side. While you have the door off look through the small glass window on the blower door an count the blinks of the light on the control board. Light code is on the door of the furnace.