When the DEFOG switch is set to ON, where does the bleed air inflow valve move?

When the DEFOG switch is set to ON, the bleed air inflow valve automatically moves to a fully open position to facilitate the defogging process. This action allows maximum bleed air to enter the system, which is essential for rapidly heating the windshield and preventing moisture buildup that can obstruct visibility. The configuration is designed to provide optimal airflow and temperature control necessary for effective defogging.

In contrast, other options suggest actions that do not correspond to the operational requirements for defogging. For instance, closing the bleed air inflow or partially opening it would reduce airflow, which contradicts the intent of ensuring clear visibility by rapidly circulating warm air. Not moving at all would likewise fail to meet the demands for defogging, as it would not introduce the necessary heated air into the cockpit. Thus, the correct operation is to have the bleed air inflow valve fully open when the DEFOG switch is activated.