An air conditioner includes an outdoor unit for circulating refrigerant, a plurality of indoor units for circulating water, and a heat exchange device configured to connect the outdoor unit to the plurality of indoor units and perform heat exchange between the refrigerant and the water. The heat exchange device includes a plurality of ports to which the plurality of indoor units are connected. The air conditioner further includes a controller configured to control flow of the water between the heat exchange device and the plurality of indoor units, and to search pipes respectively connected to the plurality of ports. The controller can control the flow of water such that water at a first temperature flows to some of the plurality of ports and the water at a second temperature lower than the first temperature flows to other some of the plurality of ports.