Patent attributes
A vehicle is disclosed that has multiple coolant paths selected by control of a valve. A valve system is configured to direct coolant from an engine to a heat exchanger according to a difference between a temperature associated with the engine and a temperature associated with the heat exchanger. The valve system is also configured to direct coolant from the engine to an electric heater and to, in response to a heat demanded from the heat exchanger being greater than a heat capability of the electric heater, request the engine to run. A method is disclosed for controlling a valve to change from an isolation position in which the valve isolates coolant circulating through an electric heater and the valve from coolant circulating through an engine to a non-isolation position in which the valve directs coolant from the engine to the electric heater.
