The pressure switch controls the fill valves, and in some cases will prevent the motor
from going into spin. It operates via an internal diaphragm which triggers one or more
switches (depending on the type of pressure switch).
Water entering the drum as the machine fills gradually floods the pressure chamber and
traps the air already in it. As the water level in the drum rises so the pressure on the
air increases, this air is then forced up a small bore tube which connects both chamber and switch. When the
correct pressure on the internal diaphragm is attained the corresponding switch is activated.
