Air conditioner and method of controlling the same

A method of operating an air conditioner comprising a compressor, a heat exchanger performing heat exchange between a refrigerant and air through movement of the air, a frost formation detector provided in the heat exchanger and a controller and wherein the method comprises the steps of:

• detecting a frost formation degree in the heat exchanger by the frost formation detector;
• outputting a detection signal that is based on the frost formation degree by the frost formation detector;
• computing a frost formation level due to freezing in the heat exchanger according to the detection signal transmitted from the frost formation detector to the controller;
• and
• performing a defrosting operation according to the frost formation level using the controller,
• wherein the frost formation detector operates via a plurality of switches,
• wherein the switches are arranged in a body provided at the heat exchanger, and
• wherein each switch comprises:
• layers of electrodes spaced apart from each other by air;
• and
• insulation parts for insulating the layers of electrodes from the heat exchanger,
• wherein each of the layers of electrodes comprises two outer electrodes spaced apart from a central electrode,
• wherein one terminal of each of the electrodes is fixed to the body, and another terminal of each electrode is inserted into the heat exchanger, so that the outer electrodes are configured to turn the switches on by bending towards and making contact with the central electrode due to the freezing in the heat exchanger.