My amana air command high efficiency 80 gas furnace is not heating the house, the inside temp is falling. Please help

Please explain in detail what happens when the thermostat is turned up. It would be best if you could have someone else turn up the thermostat while you are at the furnace.
Often there is a circuit board, either in the area of the burners or in the blower compartment which may have a blinking light on it. If you find such, count the blinks between pauses. The key to the blink code is usually on the board or on the inside of the blower door.