The invention provides a mobile container for cooling produce. The container includes a box-like housing and a plenum wall creating a plenum chamber and a treatment zone. Within the treatment zone, produce can be placed. A plurality of openings are located within the plenum wall to allow conditioning air flow to pass between the plenum chamber and the treatment zone. The openings are of a non-uniform size such that the conditioning air passes from the plenum chamber into the treatment zone through the openings in a substantially uniform manner, allowing the produce to be cooled in a substantially uniform manner.