Inverter condensing units are equipped with a control module that enables the connection of a universal outdoor unit to a freon heat exchanger in the air handling unit. Such solution makes it possible to control the efficiency of the condensing unit by means of a 0-10V DC signal sent from the air handling unit control system. Both cooling and heating operation are possible. The units have built-in expansion valves, so that no additional refrigeration fittings are needed. Kaisai condensing units may only be used with AHUs equipped with protection devices suitable for R32 flammability characteristic.