A system and method are described that help in alleviating charge imbalance issues, especially in HVAC systems that are operable in both heating and cooling modes. In various embodiments a compensator is attached to the liquid line of an outdoor heat exchanger. A heater is attached to the compensator. During cooling operations the heater is turned on to help drive refrigerant out of the compensator. During heating operations the heater is turned off, allowing excess refrigerant to migrate to the compensator and alleviate high pressure in the system.

An air conditioner (100), comprising a compressor (110), a reversing assembly (120), an outdoor heat exchanger (130), an indoor heat exchanger (140), an electric control heat sink assembly (150), a first unidirectional throttle valve (160) and a second unidirectional throttle valve (160). The electric control heat sink assembly (150) comprises an electric control component (151) and a heat dissipation assembly (152). The first unidirectional throttle valve (160), on the flow direction from a first valve port (161) to a second valve port (162), is completely turned on. On the flow direction from the second valve port (162) to the first valve port (161), the first unidirectional throttle valve (160) is a throttle component. The second unidirectional throttle valve (160), on the flow direction from a third valve port (161) to a fourth valve port (162), is completely turned on. On the flow direction from the fourth valve port (162) to the third valve port (161), the second unidirectional throttle valve (160) is a throttle component.

Provided is a heat pump system (10, 10A) for a conditioned space comprising a first thermal fluid circuit adapted to selectably operate to circulate a thermal fluid therein, and a second thermal fluid circuit adapted to selectably operate to circulate the thermal fluid therein. The first thermal fluid circuit may comprise a compressor (15), a first heat exchanger (11), and a passage (55) of a heat accumulator (50). The second thermal fluid circuit may bypass the first heat exchanger (11), or the passage (55) of the heat accumulator (50), or both. The second thermal fluid circuit may comprise the compressor (15), and a second heat exchanger (12).