Air conditioner and controlling method thereof

An air conditioner, comprising:

• an indoor unit including an indoor heat exchanger and an indoor fan;
• an outdoor unit including a compressor;
• and
• a processor configured to, based on identification of an event occurring for cleaning the indoor heat exchanger:
• identify whether a pre-set threshold time has passed after a cooling operation or a dehumidifying operation is ended, and:
• based on the pre-set threshold time being identified as having passed, control a heat-up operation to be performed to increase a temperature of a surface of the indoor heat exchanger, or
• based on the pre-set threshold time being identified as not having passed, control a drying operation to be performed to dry the indoor heat exchanger, and then control the heat-up operation to be performed,
• control at least one from among the indoor fan and the compressor to perform a pre-freezing operation to form dew at the surface of the indoor heat exchanger,
• control at least one from among the indoor fan and the compressor to perform a freezing operation to freeze the dew formed at the surface of the indoor heat exchanger to form an ice-capsule at the surface of the indoor heat exchanger, and
• control the indoor fan to perform a defrosting operation to defrost the surface of the indoor heat exchange.