A method of extracting air from an inkjet printhead includes using an air extraction chamber connected to the printhead. The air extraction chamber comprises an air chamber, a one-way relief valve having open and closed positions used in venting of the air chamber. A piston in the form of a disk is provided to vent a quantity of air from the air chamber through the one-way relief valve when it's pushed through a cylinder. The piston is moved in an opposite direction through the cylinder so that a reduced air pressure is applied to the printhead when the one-way relief valve is in its closed position.