What is the use of pressure pump in automatic washing machine?

In an automatic washing machine, the pressure pump usually refers to the drain pump, although some people use the term for a booster pump. If you mean the drain pump, its functions are:

1. Drains dirty water from the washing machine after the wash cycle.
2. Removes rinse water before the spin cycle begins.
3. Prevents water from remaining inside the drum, helping avoid bad odors and mold.
4. Ensures proper spinning because the machine will not enter the spin cycle if water has not been drained.
5. Protects internal components by preventing water overflow and keeping the wash cycle operating correctly.

Signs of a faulty drain pump

• Water remains inside the drum after washing.
• The machine does not spin.
• The machine displays a drain error code.
• Unusual humming or grinding noise from the pump.
• Water drains very slowly or not at all.

If you meant the pressure switch (water level sensor) instead of the pump, its job is to detect the water level inside the tub and signal the control board when enough water has entered. This prevents both overfilling and underfilling of the washing machine.