Provided is an air conditioner and a method of controlling the same. The method of controlling an air conditioner includes determining whether a low-load condition is satisfied on the basis of the number of indoor units or a temperature of external air, performing a low-load operation of a compressor at a preset frequency when the low-load condition is satisfied, detecting whether the operation pressure is out of a target pressure value or range while the low-load operation is performed, and bypassing a refrigerant from the compressor to a gas/liquid separator via an injection passage when the operation pressure is out of the target pressure value or range.