A system may include a fan module and a louver. The fan module includes a first housing, adapted to include a fan in a first orientation. The fan is adapted to cause air to flow into the rear side of the first housing and out of the front side of the first housing. The fan module also includes a key receptacle that is adapted to mate with a first key. The louver includes a second housing that includes a set of slats adapted as a one way valve. The second housing also includes the first key which is adapted to only mate with the key receptacle. The second housing also includes the second key which is adapted to not mate with the key receptacle.