Patent ID: 7793856

Claim:
A motor vehicle comprising: a liquid-cooled combustion engine comprising a first port through which coolant can leave the engine and a second port through which coolant can return to the engine; a driver compartment that is heated by a driver compartment heater having an inlet port through which coolant enters and an outlet port through which coolant exits and a sleeper compartment that is heated by a sleeper compartment heater having an inlet port through which coolant enters and an outlet port through which coolant exits; an auxiliary coolant heater comprising an inlet port through which coolant enters the auxiliary coolant heater for heating and an outlet port through which heated coolant exits the auxiliary coolant heater; and a coolant flow control system comprising flow paths and a valve assembly that is selectively operable to first and second states for connecting the engine ports, the driver compartment heater ports, the sleeper compartment heater ports, and the auxiliary coolant heater ports to provide, when the valve assembly is in the first state, for coolant flow from the auxiliary coolant heater outlet port to divide into a first portion that flows through the engine and a second portion that flows through a first of the two compartment heaters, and for the first and second portions to rejoin and flow through a second of the two compartment heaters before returning to the auxiliary coolant heater inlet port, and when the valve assembly is in the second state, for the entire coolant flow from the auxiliary coolant heater outlet port to flow through the engine and the second of the two compartment heaters before returning to the auxiliary coolant heater inlet port, and not to flow through the first of the two compartment heaters, wherein the first compartment heater is disposed for primarily heating the driver compartment and the second compartment heater is disposed for primarily heating the sleeper compartment and wherein the valve assembly is in series flow relation with the driver compartment heater between the location where the flow from the auxiliary coolant heater outlet port divides and the location where the first and second portions rejoin.