Which switch controls the position of the fresh air valve?

The correct choice is the ram air inflow switch, which is responsible for controlling the position of the fresh air valve in the T-6 aircraft. This switch regulates the intake of outside air into the cabin, allowing for the management of airflow based on various flight conditions and temperature preferences. It provides the pilot with the ability to enhance cabin ventilation by allowing fresh air to enter, which is crucial for maintaining a comfortable and safe environment during flight.

Understanding the function of each switch is essential; the environmental control switch manages the overall temperature and climate control systems in the aircraft, while the fresh air inflow switch specifically pertains to a more controlled intake of fresh air separate from engine or other systems. The cabin air switch typically relates to circulation and temperature control within the cabin rather than directly influencing the fresh air intake. Thus, the ram air inflow switch is the primary control for managing the flow of fresh air.