An air conditioner and control method for reducing power consumption by controlling pressure or temperature of a refrigerant. The air conditioner includes a compressor compressing a refrigerant and discharging a high pressure refrigerant gas; an outdoor heat exchanger in which the high pressure refrigerant gas is changed to a refrigerant fluid; an outdoor fan to blow outdoor air to the outdoor heat exchanger; a decompressor decompressing the refrigerant fluid into a low pressure state; an indoor heat exchanger changing the decompressed low pressure refrigerant fluid to a refrigerant gas; and a controller configured to control pressure or temperature of the refrigerant based on an operation condition including at least two of a first condition determined based on an installation environment, a second condition determined based on an optimal compression ratio of the compressor, a third condition determined based on outdoor temperature, and a fourth condition set as a default value.