A plenum chamber is a pressurised housing containing a fluid at positive pressure. One of its functions is to equalise pressure for more even distribution, compensating for irregular supply or demand.

Where is the plenum chamber?

The plenum chamber is a chamber located in front of the windshield, where air pressure is above atmospheric. It provides a volume of air which is drawn into the car from the chamber through the heater, air-conditioner or vents.

What is the point of a plenum?

A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure.