What is the resulting action if both zone controller channels fail?

When both zone controller channels fail on an A320 aircraft, the system is unable to perform its normal functions effectively. The zone controllers are responsible for managing air conditioning and temperature control throughout the aircraft. Their failure results in a lack of communication and control over the pack configurations.

As a consequence, the ECAM (Electronic Centralized Aircraft Monitor) will show a PACK REG message indicating that there is an issue with the pack regulation. This alert signals to the crew that the system is in a degraded state and proper temperature control cannot be maintained, reflecting the failure of the zone control channels.

The other choices suggest normal operations or functionalities that would not occur in the event of such a failure. Thus, the mention of the PACK REG message underlines the severity of the situation, highlighting a critical failure in system management and indicating the need for further action or troubleshooting by the flight crew.