A vehicle includes a refrigerant system having a chiller and a coolant system having a chiller loop and a radiator loop. The chiller loop is arranged to circulate coolant through the chiller, and the radiator loop is arranged to circulate coolant through a battery, a radiator, and a bypass valve connected to a bypass conduit. A controller is configured to, in response to an ambient-air temperature exceeding a battery-coolant temperature, actuate the valve to circulate coolant to the bypass conduit to skip the radiator.