Air conditioner

An air conditioner comprising:

• an indoor unit having an indoor heat exchanger installed therein;
• a first outdoor unit having a first outdoor heat exchanger and a first compressor installed therein;
• a second outdoor unit having a second outdoor heat exchanger and a second compressor installed therein;
• an auxiliary module configured to connect the indoor unit, the first outdoor unit, and the second outdoor unit to each other;
• a first connection line to which the auxiliary module and the first outdoor unit are connected;
• a second connection line to which the auxiliary module and the second outdoor unit are connected;
• and
• a two-stage compression line configured to connect the first outdoor unit and the second outdoor unit to each other,
• wherein the two-stage compression line includes:
• a first two-stage compression line configured to allow a refrigerant that exchanges heat by the second outdoor heat exchanger to flow to the first outdoor unit;
• and
• a second two-stage compression line configured to allow a refrigerant compressed by the first compressor to flow to the second outdoor unit,
• wherein the first connection line includes a first heat exchanger input and output line to which the auxiliary module and the first outdoor heat exchanger are connected,
• wherein the auxiliary module further includes an auxiliary module injection line configured to connect the first heat exchanger input and output line and the second two-stage compression line to each other, and
• wherein the auxiliary module injection line includes installed therein:
• an auxiliary module injection expansion valve configured to expand a refrigerant flowing in the auxiliary module injection line from the first heat exchanger input and output line;
• and
• an auxiliary module injection heat exchanger configured to exchange heat between a transmitted through the auxiliary module injection expansion valve and a refrigerant flowing in the first heat exchanger input and output line.