In one instance, a cooling unit for use as an aspect of a cooling system includes a cabinet having a plurality of panels and having an interior, a front face with a fan aperture formed in the front face, and a bottom panel. The cooling unit further includes a drain pan below the bottom panel. The cooling unit also includes a plurality of guide-rail slide and track assemblies coupled between at least a portion of the cabinet and the drain pan for providing controlled movement of the drain pan between an operational position and a maintenance position. Other cooling units are disclosed with drain pans that may be lowered by a single technician.