How does the A320 environmental control system regulate cabin temperature and pressurization?

• A. The ECS uses packs for temperature control and a pressurization controller with an outflow valve to maintain cabin pressure and altitude.
• B. The ECS uses packs only for temperature control; pressurization is managed manually.
• C. The ECS relies on ambient temperature and crew adjustments with no automated control.
• D. The ECS does not regulate cabin pressure.

Answer: (A)

Temperature in the A320 is controlled by the environmental control system’s air conditioning packs. These packs take bleed air from the engines (or the APU), run it through heat exchangers and conditioning cycles, and deliver air at the chosen cabin temperature. The system automatically trims the heated or cooled air to the setpoint so that the cabin stays comfortable without manual intervention.

Pressurization, separate from the temperature control, is managed by a dedicated pressurization controller. It monitors the cabin altitude and compares it with the selected pressure schedule. To hold the cabin at the desired altitude and maintain the required cabin differential pressure, it modulates the outflow valve, venting excess air to the outside as needed. This automated control adjusts during climbs, cruises, and descents to keep the cabin within safe and comfortable limits. The ram air path can provide cooling or assist in ventilation, but the primary mechanism for maintaining cabin pressure is the outflow valve driven by the pressurization controller.

So, the packs handle temperature control, while a pressurization controller with the outflow valve maintains cabin pressure and altitude.