Air conditioner

An air conditioner, comprising:

• a first compressor that compresses a refrigerant;
• a second compressor that compresses the refrigerant;
• an indoor heat exchanger that performs heat exchange between the refrigerant and air;
• a first four-way valve having a first port connected to an outlet-side of the first compressor;
• a first outdoor heat exchanger connected to a second port of the first four-way valve;
• a first three-way valve connected to a third port of the first four-way valve;
• a second four-way valve having a first port connected to an outlet-side of the second compressor;
• a second outdoor heat exchanger connected to a second port of the second four-way valve;
• a second three-way valve connected to a third port of the second four-way valve;
• a first valve pipe that connects a fourth port of the first four-way valve and a fourth port of the second four-way valve;
• a second valve pipe that connects the first valve and the second valve;
• a third four-way valve having a first port connected to the first valve pipe, a second port connected to the second valve pipe, a third port connected to inlet-sides of the first compressor and the second compressor, and a fourth port connected to the indoor heat exchanger;
• and
• a controller that selectively connects the ports of the first four-way valve, the second four-way valve, and the third four-way valve based on a cooling mode of an indoor unit, a heating mode of the indoor unit, a defrost mode of the first outdoor heat exchanger, or a defrost mode of the second outdoor heat exchanger.