A vehicle battery temperature control system includes a battery, a housing, a heat exchanger, a valve and a sensor. The battery has a heat sink that transfers thermal energy. The housing has a chamber that contains the battery and saturated liquid coolant that substantially immerses the heat sink to receive the thermal energy to cause a phase change of the coolant from a liquid to a vapor. The heat exchanger removes thermal energy from the vapor to change the vapor to liquid, and returns the liquid to the chamber. The valve selectively fluidly couples the chamber to an air-conditioning system to enhance cooling of the coolant. The sensor detects a characteristic of the coolant and signals operation of the valve to fluidly couple the chamber to the air-conditioning refrigeration system to increase removal of thermal energy from the coolant based on a relationship between the characteristic of the coolant and a threshold.