An indoor apparatus, suitable for being operated with a reduced refrigerant noise level in an air-conditioning system, wherein the indoor apparatus includes: a heat-exchanger for exchanging heat between refrigerant and indoor air; a fan rotating to provide air to flow to the heat-exchanger; and an expansion valve for expanding refrigerant discharged from the heat-exchanger, wherein the indoor apparatus further includes: a first temperature sensor disposed on a first conduit for supplying refrigerant to the heat-exchanger, wherein the first temperature sensor detects a first temperature of refrigerant to be fed into the heat-exchanger; a second temperature sensor disposed on a second conduit for receiving refrigerant from the heat-exchanger, wherein the second temperature sensor detects a second temperature of refrigerant discharged from the heat-exchanger; a third temperature sensor disposed on a housing of the indoor apparatus for detecting a discharge temperature of the indoor apparatus; and a controller configured for estimating a load of the indoor apparatus based on the discharge temperature detected by the third temperature sensor, and for increasing or decreasing an air flow rate of the fan based on the estimated load, the indoor apparatus being characterized in that the indoor apparatus further includes a fourth temperature sensor for detecting a temperature of air inside the indoor apparatus, and wherein the fourth temperature sensor is disposed adjacent to the first conduit such that the heat-exchanger is interposed between the fan and the fourth temperature sensor. a heat-exchanger for exchanging heat between refrigerant and indoor air; a fan rotating to provide air to flow to the heat-exchanger; and an expansion valve for expanding refrigerant discharged from the heat-exchanger, wherein the indoor apparatus further includes: a first temperature sensor disposed on a first conduit for supplying refrigerant to the heat-exchanger, wherein the first temperature sensor detects a first temperature of refrigerant to be fed into the heat-exchanger; a second temperature sensor disposed on a second conduit for receiving refrigerant from the heat-exchanger, wherein the second temperature sensor detects a second temperature of refrigerant discharged from the heat-exchanger; a third temperature sensor disposed on a housing of the indoor apparatus for detecting a discharge temperature of the indoor apparatus; and a controller configured for estimating a load of the indoor apparatus based on the discharge temperature detected by the third temperature sensor, and for increasing or decreasing an air flow rate of the fan based on the estimated load, the indoor apparatus being characterized in that the indoor apparatus further includes a fourth temperature sensor for detecting a temperature of air inside the indoor apparatus, and wherein the fourth temperature sensor is disposed adjacent to the first conduit such that the heat-exchanger is interposed between the fan and the fourth temperature sensor. a first temperature sensor disposed on a first conduit for supplying refrigerant to the heat-exchanger, wherein the first temperature sensor detects a first temperature of refrigerant to be fed into the heat-exchanger; a second temperature sensor disposed on a second conduit for receiving refrigerant from the heat-exchanger, wherein the second temperature sensor detects a second temperature of refrigerant discharged from the heat-exchanger; a third temperature sensor disposed on a housing of the indoor apparatus for detecting a discharge temperature of the indoor apparatus; and a controller configured for estimating a load of the indoor apparatus based on the discharge temperature detected by the third temperature sensor, and for increasing or decreasing an air flow rate of the fan based on the estimated load, the indoor apparatus being characterized in that the indoor apparatus further includes a fourth temperature sensor for detecting a temperature of air inside the indoor apparatus, and wherein the fourth temperature sensor is disposed adjacent to the first conduit such that the heat-exchanger is interposed between the fan and the fourth temperature sensor.