Abstract: A system for mixing air for a vehicle HVAC (heating, ventilation, air-conditioning) component, includes a first inlet for outdoor air from an exterior space of the vehicle; a first fan in communication with the first inlet to control (only) an air inflow through the first inlet; a second inlet for indoor air from an interior space of the vehicle; and a second fan in communication with the second inlet to control (only) an air inflow through the second inlet. The first fan and the second fan are independently controllable to provide a desired mix of air to the vehicle HVAC component.

Abstract: An air filter for an air conditioning system of a railway vehicle includes a first layer of a first filter medium with a first medium surface, a second layer of a second filter medium with a second medium surface, and a peripheral frame to hold the first layer and the second layer adjacent to each other, wherein the second surface medium area is non-flat and provides a larger filter surface area than the first layer.