What occurs when the DUMP button is pressed in AUTO or LFE mode?

When the DUMP button is pressed in AUTO or LFE mode, it activates a specific cabin pressurization response intended to rapidly change the cabin environment. Specifically, pressing the DUMP button results in both the packs and recirculation fans being turned off. This is essential as it allows for an immediate drop in cabin pressure, facilitating a rapid ascent for the cabin to achieve a more neutral pressure state.

Additionally, the system allows the cabin to climb at a rate of 2000 feet per minute, ceasing at a maximum altitude of 12,400 feet. This coordinated action between shutting down the environmental systems and controlling the cabin altitude serves to stabilize the pressure in emergencies or operational requirements, achieving a balance necessary for situations where cabin pressure needs to be rapidly altered.

The combination of both the cabin ascent and the deactivation of the environmental systems is the key reason that this answer is the most comprehensive and accurate for this scenario.