If the primary pack controller channel fails, what happens?

When the primary pack controller channel fails, the pack flow is fixed at the pre-failure setting. This occurs because the backup control system takes over the operation of the air conditioning pack but does not have the capability to adjust the flow dynamically. As a result, the airflow remains constant at the level it was set prior to the failure, which may affect passenger comfort and cabin conditions but ensures that the pack continues to provide necessary airflow. This behavior is designed to maintain a level of operational functionality despite the failure, as the system prioritizes safety and stability in cabin pressure and temperature.

In contrast, pack operation is indeed affected since the controller's dynamic adjustments are no longer in effect. The ECAM pack information continues to display even in a failure scenario, providing the flight crew with necessary system information. Lastly, the pack outlet temperature is not controlled by the anti-ice valve, which is a separate system aimed at preventing ice accumulation rather than directly managing temperature output of the air conditioning system.