to operate the uv lamps during a high level cooling mode of the air conditioner the air conditioner is turned on at step 10 so that the input power unit 140 supplies electric power to the air conditioner thereafter a desired operational mode is selected by a user using the function selecting unit 130 at step 15 the controller 100 checks whether the selected operational mode is the high level cooling mode when controller 100 determines that the high level cooling mode was selected the controller 100 calculates a difference between the present room temperature sensed by the temperature sensing unit 110 and the target room temperature preset by the temperature setting unit 120 the controller 100 thereafter drives the compressor and blower fan 20 at rpms of higher than the reference rpms which were preset according to the difference between the present and target room temperatures by at least one stage at step 20 the controller 100 outputs a lamp start signal to the lamp driving unit 180 in order to turn on the uv lamps 60 and 70 upon receiving the lamp start signal the unit 180 turns on the uv lamps 60 and 70 the lamps 60 and 70 emit ultraviolet rays thus killing the harmful germs and fungi laden in the room air which is drawn into the housing 1.