Heat exchanger unit and air conditioner using the same

An air conditioner comprising:

• a heat exchanger unit comprising:
• a heat exchanging section that includes:
• a plurality of heat transfer fins;
• and
• a plurality of heat transfer tubes;
• and
• a fan that generates an air flow that passes in a vertical direction substantially parallel to a direction of gravity when the heat exchanger unit is installed, wherein
• each of the plurality of heat transfer tubes:
• extends in a first horizontal direction substantially perpendicular to the vertical direction when the heat exchanger unit is installed, and
• passes through a corresponding one of the plurality of heat transfer fins,
• in the heat exchanging section, the plurality of heat transfer tubes are arranged in L levels or more in the vertical direction and in M rows in a second horizontal direction that is perpendicular to the vertical direction and the first horizontal direction,
• each of the plurality of heat transfer tubes belongs to one of N paths,
• 3≤M<N,
• all of the N paths pass through all of the M rows at least once,
• inlets of all of the N paths are disposed at a first end of the heat exchanging section in the vertical direction,
• outlets of all of the N paths are disposed at a second end of the heat exchanging section in the vertical direction,
• a refrigerant flows through each of the N paths from one of the inlets to a corresponding one of the outlets,
• the refrigerant that flows through one of the plurality of heat transfer tubes at a first level among the L levels subsequently flows at a second level among the L levels, where the first level is not closer to the corresponding one of the outlets than the second level is in any part of the N paths,
• the heat exchanger unit is installed in a same vertical orientation when the fan is installed upside down such that a direction of the air flow is reversed, and
• each of the N paths runs back and forth at least once between a row that is disposed most upstream with respect to the second horizontal direction and a row that is disposed most downstream with respect to the second horizontal direction.