An embodiment of a modular electronic enclosure is provided as including a chassis having a first portion defining a first compartment, and a second portion defining a second compartment. First and second replaceable units are replaceably received within the first and second compartments, respectively. The modular electronic enclosure also has a fan unit that is replaceably received within a compartment defined by the first portion or the second portion. The fan unit is configured to pull in cooling air through the first portion and exhaust pressurized cooling air through the second portion. A method of cooling a modular electronic enclosure defining first and second compartments is also provided.