24 to maintain the valve temperature of the coolant as close as possible to the valve set point temperature in the propulsion system 12 the coolant absorbs heat and then is distributed through the coolant outlet line 30 the valve set point temperature ensures that the valve temperature of the coolant flowing into the propulsion system 12 is such that absorption of heat from the propulsion system 12 by the coolant is sufficient to facilitate optimal energy consumption and or performance from the propulsion system 12 in the absence of a heating situation the coolant heater 14 is typically not operated to facilitate heated air demands inside the vehicle cabin therefore in the absence of a heating situation vehicle energy is typically not consumed by the coolant heater 14 at the onset of a heating situation however the heater set point temperature requirements must now be met to facilitate the increased demand for heated air inside the vehicle cabin accordingly the coolant heater 14 is operated to realize the heater set point temperature which is typically higher than the valve set point temperature as indicated in step 4 of fig2 accordingly the coolant heater 14 augments the temperature of the coolant such that the heater temperature of the coolant rises and approaches or meets the raised or modified heater set point temperature this heating of the coolant by the coolant heater 14 ensures that thermal exchange between the heated coolant and air in the heater core 18.