Abstract: An air conditioning system for use in a hybrid-electric vehicle having an engine and a cabin. The system includes a refrigerant loop and a coolant loop. A phase change heat exchanger including a first tube in fluid communication with the refrigerant loop and a second tube in fluid communication with the coolant loop. The first and second tubes abut one another for conducting heat from the coolant in the coolant loop to the first refrigerant in the refrigerant loop when the vehicle is operating with the engine running. The phase change heat exchanger further includes a chamber abutting the first and second tubes for storing a phase change material. The phase change material conducts heat to the first refrigerant to freeze the phase change material when the vehicle is operating with the engine running and receives heat from the coolant to cool the coolant when the engine is not running.