Air conditioner system including refrigerant cycle circuit for oil flow blocking

An air conditioner system comprising:

• a compressor;
• a four-way valve;
• an oil separator disposed between the compressor and the four-way valve;
• a pressure sensor configured to detect a pressure of a refrigerant passing through the oil separator after being discharged from the compressor;
• a first temperature sensor configured to detect a temperature of the compressor;
• a second temperature sensor configured to detect a discharge temperature of the compressor;
• a blocking valve, disposed between the oil separator and the four-way valve, having an opened state in which the refrigerant passing through the oil separator after being discharged from the compressor passes through the blocking valve to the four-way valve and a closed state in which the refrigerant passing through the oil separator after being discharged from the compressor is blocked by the blocking valve from passing to the four-way valve;
• a circulation line having an input end downstream of the oil separator and upstream of the blocking valve, the circulation line configured to, when the blocking valve is in the closed state, provide a path for introducing the refrigerant passing through the oil separator after being discharged from the compressor into the input end and then back into the compressor;
• a heat exchanger;
• a liquid separator;
• and
• a controller configured to:
• when the air conditioner system is started in a heating mode,
• control the blocking valve to be in the closed state at a time when the compressor is started or within a predetermined time from the time when the compressor is started,
• control the four-way valve to set a refrigerant path in which the refrigerant passing through the oil separator after being discharged from the compressor is introducible into the four-way valve, to then travel through the indoor unit to the heat exchanger, to then travel through the four-way valve, and to then travel through the liquid separator to the compressor,
• when the temperature of the compressor detected by the first temperature sensor is higher than a saturation temperature corresponding to the pressure of the refrigerant passing through the oil separator after being discharged from the compressor detected by the pressure sensor by a predetermined first value or more,
• identify whether the discharge temperature of the compressor detected by the second temperature sensor is higher than the saturation temperature corresponding to the pressure of the refrigerant passing through the oil separator after being discharged from the compressor detected by the pressure sensor by a predetermined second value or more, and
• when the discharge temperature of the compressor is identified to be higher than the saturation temperature corresponding to the pressure of the refrigerant passing through the oil separator after being discharged from the compressor detected by the pressure sensor by the predetermined second value or more, control the blocking valve to change from the closed state to be in the opened state,
• when the air conditioner is started in a cooling mode,
• control the four-way valve to set a refrigerant path in which the refrigerant passing through the oil separator after being discharged from the compressor is introducible into the four-way valve, to then travel through the heat exchanger to the indoor unit, to then travel through the four-way valve, and to then travel through the liquid separator to the compressor, and
• control the blocking valve to be in the opened state.