What does switching the cabin pressure MODE SEL Switch to MAN allow you to do?

Switching the cabin pressure MODE SEL switch to MAN allows the crew to manually control the outflow valve, which regulates the cabin pressure. In the manual mode, pilots can directly adjust the position of the outflow valve to maintain the desired cabin pressure, especially in abnormal situations or when the automatic systems are not functioning as intended. This manual adjustment capability is crucial for ensuring passenger comfort and maintaining safety during flight.

The other options, while related to aircraft systems, do not correspond to the function of the MODE SEL switch in manual mode. The inlet valves, pack flow valves, and pack outflow valves operate under different systems and are managed automatically or through other controls and are not directly influenced by switching the cabin pressure control to manual mode.