An outdoor unit according to the present disclosure includes: a compressor that sucks refrigerant, compresses the sucked refrigerant, and discharges the compressed refrigerant; a first refrigerant flow switching device that switches a flow passage for the refrigerant between a flow passage for a cooling operation and a flow passage for a heating operation; a heat-source-side heat exchanger that causes heat exchange to be performed between the refrigerant and external fluid; a heat-source-side backflow prevention device and a connection pipe that are included in a flow passage for the refrigerant in which an outlet from which the refrigerant flows to an outside region and an inlet into which the refrigerant flows from the outside region are unchanged regardless of which of the cooling operation and the heating operation is performed; and a flow passage pipe through which part of the refrigerant having flowed from the inlet passes in the cooling operation.

An outdoor unit according to the present disclosure includes: a compressor that sucks refrigerant, compresses the sucked refrigerant, and discharges the compressed refrigerant; a first refrigerant flow switching device that switches a flow passage for the refrigerant between a flow passage for a cooling operation and a flow passage for a heating operation; a heat-source-side heat exchanger that causes heat exchange to be performed between the refrigerant and external fluid; a heat-source-side backflow prevention device and a connection pipe that are included in a flow passage for the refrigerant in which an outlet from which the refrigerant flows to an outside region and an inlet into which the refrigerant flows from the outside region are unchanged regardless of which of the cooling operation and the heating operation is performed; and a flow passage pipe through which part of the refrigerant having flowed from the inlet passes in the cooling operation.

An outdoor unit of an air conditioner having an expansion valve unit. The outdoor unit of the air conditioner includes a compressor, a heat exchanger configured to exchange heat between outdoor air and refrigerant compressed by the compressor, an expansion valve unit configured to decompress the refrigerant discharged from the heat exchanger, a refrigerant pipe configured to deliver the refrigerant, which is decompressed and expanded by the expansion valve unit, to the indoor unit of the air conditioner, and a bracket configured to support the expansion valve unit. The expansion valve unit includes an expansion valve, a first connection portion configured to connect the expansion valve to the heat exchanger, and a second connection portion configured to connect the expansion valve to the refrigerant pipe. The expansion valve, and one of the first connection portion or the second connection portion are fixed to the bracket.

An air conditioning apparatus 1 includes a compressor (321), an indoor heat exchanger (242) that is a use-side heat exchanger that exchanges heat with first air (F1), an outdoor heat exchanger (323) that is a heat-source-side heat exchanger that exchanges heat with second air, a refrigerant, a first duct (209), and a casing (230). The refrigerant contains at least 1,2-difluoroethylene, and circulates in the compressor (321), the indoor heat exchanger (242), and the outdoor heat exchanger (323) to repeat a refrigeration cycle. The first duct (209) supplies the first air (F1) to a plurality of rooms in an interior. The casing (230) includes a use-side space (SP2) that is connected to the first duct (209) and that accommodates the indoor heat exchanger (242). The casing (230) is configured to allow the first air (F1) after heat exchange with the refrigerant at the indoor heat exchanger (242) to be sent out to the first duct (209).

An air conditioning apparatus 1 includes a compressor (321), an indoor heat exchanger (242) that is a use-side heat exchanger that exchanges heat with first air (F1), an outdoor heat exchanger (323) that is a heat-source-side heat exchanger that exchanges heat with second air, a refrigerant, a first duct (209), and a casing (230). The refrigerant contains at least 1,2-difluoroethylene, and circulates in the compressor (321), the indoor heat exchanger (242), and the outdoor heat exchanger (323) to repeat a refrigeration cycle. The first duct (209) supplies the first air (F1) to a plurality of rooms in an interior. The casing (230) includes a use-side space (SP2) that is connected to the first duct (209) and that accommodates the indoor heat exchanger (242). The casing (230) is configured to allow the first air (F1) after heat exchange with the refrigerant at the indoor heat exchanger (242) to be sent out to the first duct (209).

An air conditioner includes: a heat exchanger; a refrigerant flow divider causes a liquid refrigerant to be divided and to flow to the heat exchanger; and a case that includes a bottom plate, and accommodates the heat exchanger and the refrigerant flow divider. A first drain unit having a first opening for drainage is disposed on the bottom plate. The refrigerant flow divider includes: a flow divider body including a branching flow path; and refrigerant tubes that project downward from a lower surface of the flow divider body and then bend upward to connect to the heat exchanger at a position above the lower surface. All of the refrigerant tubes have lowermost ends that overlap with the first drain unit when viewed in a vertical direction.

An air conditioner includes: a heat exchanger; a refrigerant flow divider causes a liquid refrigerant to be divided and to flow to the heat exchanger; and a case that includes a bottom plate, and accommodates the heat exchanger and the refrigerant flow divider. A first drain unit having a first opening for drainage is disposed on the bottom plate. The refrigerant flow divider includes: a flow divider body including a branching flow path; and refrigerant tubes that project downward from a lower surface of the flow divider body and then bend upward to connect to the heat exchanger at a position above the lower surface. All of the refrigerant tubes have lowermost ends that overlap with the first drain unit when viewed in a vertical direction.

A diagnosis control method of an air conditioner is provided to clearly inform a user of an air conditioner installation error. The diagnosis control method includes receiving a test run command or a self-diagnosis command for diagnosis of the air conditioner, performing a first test run to diagnose an assembly state of the air conditioner, performing a second test run to diagnose pipe connection of the air conditioner and an amount of refrigerant in the air conditioner, performing a determination including diagnosing a state of the air conditioner based on operation results of the first test run and the second test run, and displaying the diagnosis result through a display device provided at an indoor unit of the air conditioner.

Provided is an outdoor unit for use in a refrigeration cycle apparatus circulating refrigerant mixture inclusive of 1,1,2-trifluoroethylene, the outdoor unit including: a casing; a pipe configured to allow the refrigerant mixture to flow through the pipe, the pipe being accommodated inside the casing and including a bend portion, the bend portion including a breakage-guide structure having a pressure resistance lower than a pressure resistance of rest of the pipe; and a plate interposed between the breakage-guide structure and outside of the casing.

Provided is an outdoor unit for use in a refrigeration cycle apparatus circulating refrigerant mixture inclusive of 1,1,2-trifluoroethylene, the outdoor unit including: a casing; a pipe configured to allow the refrigerant mixture to flow through the pipe, the pipe being accommodated inside the casing and including a bend portion, the bend portion including a breakage-guide structure having a pressure resistance lower than a pressure resistance of rest of the pipe; and a plate interposed between the breakage-guide structure and outside of the casing.