A filter element for filtering a fluid has at least two areal filter medium bodies arranged axially to be flowed through sequentially by the fluid. The filter medium bodies include an outermost downstream filter medium body and an outermost upstream filter medium body. The outermost downstream and outermost upstream filter medium bodies are arranged radially inside a frame element. The outermost downstream filter medium body has a circumferential downstream molded element and is connected by the circumferential downstream molded element to the frame element. The outermost upstream filter medium body has a circumferential upstream molded element and is connected by the circumferential upstream molded element to the frame element. The circumferential upstream molded element is connected to an upstream frame element end. The circumferential downstream molded element is connected to a downstream frame element end. The filter element is arranged in a filter housing of a filter system.

The indoor unit for the air conditioner according to the present invention includes: a cabinet assembly forming an external appearance of the indoor unit and having an air suction port formed in a rear of the cabinet assembly; a filter module disposed at the air suction port to filter dust contained in air being introduced through the air suction port; a filter cleaner configured to move upward and downward in a rear of the filter module to remove foreign substances stuck in the filter module; a guide rail vertically disposed on one side of the filter module and configured to guide upward and downward movement of the filter cleaner.

A modular air treatment assembly includes a base module, at least one intermediate module stacked on the base module, the at least one intermediate module removably connected to the base module, and a top module stacked on the at least one intermediate module, the at least one top module removably connected to the intermediate module, wherein electrical power provided to the base module is communicated to the at least one intermediate module and the top module.