Abstract: An improved modular air conditioning apparatus featuring selective panel enclosures, plug-in controls, orientation selection and servicing capability for the simultaneous provision of air conditioning to a first room area and a second room area, the apparatus disposable between wall partitions or the like separating the first and second room areas. The apparatus comprises a frame assembly having a first open box frame and a second open box frame, each having three access sides. A blower and heat exchanger are disposed in an operating section of each of the open box frames, and these are removable through an access port provided by the removal of an intake grille disposed at one of the access sides on each of the open box frames. Riser pipes disposed in a vertical riser duct connect with other like units and supply hot or chilled water to heat exchangers.