Air conditioner

An air conditioner, comprising:

• a case into which outdoor air flows;
• a first heat exchanger disposed in the air flow that exchanges heat between the air and a refrigerant;
• a second heat exchanger, through which the refrigerant selectively flows, and that exchanges heat between the air and the refrigerant;
• a liquid pipe connected to each of the first heat exchanger and the second heat exchanger, through which liquid refrigerant flows;
• a high-pressure gas pipe connected to each of the first heat exchanger and the second heat exchanger, through which gaseous refrigerant flows;
• a low-pressure gas pipe through which the gaseous refrigerant discharged from the first heat exchanger and the second heat exchanger flows;
• a high-pressure gas pipe valve installed in the high-pressure gas pipe;
• a low-pressure gas pipe valve installed in the low-pressure gas pipe;
• an expansion valve installed in the liquid pipe;
• and
• a controller configured to control an opening degree of the low-pressure gas pipe valve based on a temperature of the refrigerant flowing through the first heat exchanger, wherein the low-pressure gas pipe valve adjusts a pressure of refrigerant passing by controlling the opening degree, and wherein a flow rate coefficient of the low-pressure gas pipe valve is greater than a flow rate coefficient of the expansion valve.