An air conditioner system (10) comprises a compressor (130), a condenser (C), an expander (120), an evaporator (E) and a bypass pipeline configured to guide the evaporated refrigerant from the evaporator (E) to the condenser (C), wherein the bypass pipeline comprises: a fist bypass pipe (171) configured to guide at least partially the evaporated refrigerant from the evaporator (E) to the condenser (C); a second bypass pipe (170) coupled to the first bypass pipe (171) to be configured to allow heat exchange between refrigerant in the condenser (C) and refrigerant therein; and a third bypass pipe (172) coupled to the second bypass pipe (170) to be configured to guide the refrigerant from the second bypass pipe (170) out of the condenser (C).