What component takes over if the primary pack controller channel fails?

The secondary pack controller channel serves as a backup to the primary pack controller channel in an A320. In the event of a failure in the primary channel, the system automatically switches to the secondary channel to maintain the operation of the air conditioning packs. This redundancy is critical for ensuring continuous climate control within the aircraft's cabin, thereby enhancing passenger comfort and safety.

The flight deck controls, while essential for overall aircraft operation, do not directly assume control over the pack system in the case of a controller failure. Similarly, while the ECAM system monitors and provides alerts regarding system statuses, it does not take over the control function of the pack controller. The cabin temperature regulator is involved in adjusting cabin conditions but relies on the pack controller systems to function properly. Therefore, the secondary pack controller channel is specifically designed to take over seamlessly if the primary system encounters a fault.