It's the actuator just above the gas pedal. They usually have a tag with a part number on them. You can observe it while you move the controls and see if it's moving. If your dash deteriorates and cracks at the defrost vents parts of it can cause the door to stick.
Mode and temperature (heater) use the same actuator. As mentioned above, see if it’s actually turning (there’s a notched silver position indicator dial on it) or if the connected linkage arms are intact.