Abstract: In one embodiment, a floor pan assembly for use with an evaporative cooler structure includes a base that has a first height and includes a plurality of preformed first members that are located at select locations around a bottom edge of the base. The assembly also has at least one shim member that intimately engages one of the preformed first members to locally increase the height of the base relative to a ground surface. An upper floor pan is disposed above the base and includes a floor and side walls that define an interior space for collecting fluid, the upper floor pan including at least one drain port.