Heat pump system for a vehicle

A heat pump system for a vehicle, comprising:

• an air conditioner unit comprising a compressor, a second heat-exchanger, a third heat-exchanger, and a fourth heat-exchanger that are connected through a refrigerant line so as to circulate refrigerant through a refrigerant line;
• and
• a chiller connected to the refrigerant line through a second connection line, and configured to exchange heat between the refrigerant supplied from the air conditioner unit and a coolant to adjust a temperature of the coolant,
• wherein the air conditioner unit further comprises:
• a first control apparatus provided in the refrigerant line downstream of the compressor;
• a first heat-exchanger connected to the first control apparatus through a first connection line;
• a second control apparatus provided at a position where the refrigerant line and the second connection line are connected upstream of the chiller and the fourth heat-exchanger;
• a third control apparatus provided in the refrigerant line between the fourth heat-exchanger and the compressor;
• a third connection line including:
• a first end connected to the refrigerant line between the fourth heat-exchanger and the third control apparatus, and a second end connected to the refrigerant line between the third heat-exchanger and the second control apparatus;
• and
• a fourth control apparatus provided in the third connection line.