An air conditioning system comprising: a controller for selecting an operation mode and an air volume rate; an air cleaning unit including a signal receiving portion receiving instruction signals from the controller, a control portion receiving the instruction from the signal receiving portion, and a driving portion actuating a fan motor and other components according to the instruction inputted to the control portion; a heat recovery ventilator including a control portion receiving control signals from the control portion of the air cleaning unit, and a driving portion actuating a fan motor or other components according to an instruction from the control portion of the heat recovery ventilator; and a duct member connecting the air cleaning unit and the heat recovery ventilator, characterized in that the controller includes: a display window for showing operational states of the air conditioning system; a power key for actuating a starting and stopping of the system when selected by a user; a scheduler key for scheduling the operation of the air conditioning system; a mode selection key for selecting ventilation mode and/or cleaning mode; an air volume control key for actuating a control of air volume outputs of the fans installed in the air cleaning unit and the heat recovery ventilator; and a fast/power-saving selection key for selecting a fast operation or a power-saving operation for the air conditioning system, wherein the controller and the control portion of the air cleaning unit are connected to each other via a cable or radio waves. a controller for selecting an operation mode and an air volume rate; an air cleaning unit including a signal receiving portion receiving instruction signals from the controller, a control portion receiving the instruction from the signal receiving portion, and a driving portion actuating a fan motor and other components according to the instruction inputted to the control portion; a heat recovery ventilator including a control portion receiving control signals from the control portion of the air cleaning unit, and a driving portion actuating a fan motor or other components according to an instruction from the control portion of the heat recovery ventilator; and a duct member connecting the air cleaning unit and the heat recovery ventilator, characterized in that the controller includes: a display window for showing operational states of the air conditioning system; a power key for actuating a starting and stopping of the system when selected by a user; a scheduler key for scheduling the operation of the air conditioning system; a mode selection key for selecting ventilation mode and/or cleaning mode; an air volume control key for actuating a control of air volume outputs of the fans installed in the air cleaning unit and the heat recovery ventilator; and a fast/power-saving selection key for selecting a fast operation or a power-saving operation for the air conditioning system, wherein the controller and the control portion of the air cleaning unit are connected to each other via a cable or radio waves. a display window for showing operational states of the air conditioning system; a power key for actuating a starting and stopping of the system when selected by a user; a scheduler key for scheduling the operation of the air conditioning system; a mode selection key for selecting ventilation mode and/or cleaning mode; an air volume control key for actuating a control of air volume outputs of the fans installed in the air cleaning unit and the heat recovery ventilator; and a fast/power-saving selection key for selecting a fast operation or a power-saving operation for the air conditioning system, wherein the controller and the control portion of the air cleaning unit are connected to each other via a cable or radio waves.