Abstract: An extraction machine of this invention comprises a main housing. A vacuum pump in the main housing operates to create a vacuum to extract liquid from the surface. A motor in the main housing drives the vacuum pump, the vacuum pump having an exhaust. An exhaust duct conducts exhaust air from the exhaust of the vacuum pump to an opening in the main housing for exhaust to the environment. A constriction in the exhaust duct reduces the pressure of exhaust air flowing through the exhaust duct from a first pressure upstream from the constriction to a second lower pressure in a low pressure zone adjacent the constriction. A compartment has an inlet for entry of ambient air into the compartment and an outlet for exit of air from the compartment. A second motor is located within the compartment. A cooling duct has an inlet communicating with the outlet of the compartment and an outlet communicating with the low pressure zone in the exhaust duct.