A
system and method of selecting air intake between 100%
fresh air mode and 100% recirculated air mode for optimum heating / cooling performance, fuel economy and / or
high voltage (HV) battery
power consumption is disclosed. The
system and method includes a partial recirculation control strategy in which the air inlet door is moved progressively to any position by taking into account cooling / heating loads and cabin
fogging probability. As cooling / heating loads increase the air inlet door moves toward 100% recirculation mode. As
fogging probability increases the air inlet door moves toward 100%
fresh air mode. By selectively choosing a position between 100% recirculation and 100%
fresh air, fuel economy and / or HV battery
power consumption is optimized without compromising passenger comfort or causing
fogging on interior glass surfaces. In cooling applications the compressor load is minimized and
air conditioning performance is improved due to the reduced
evaporator cooling load. The direct result of this improvement is increased fuel economy in the case of the internal
combustion vehicle, reduced engine on time in the case of the
hybrid electric vehicle (due to reduced HV battery
power consumption), and reduced HV battery power consumption in the case of the
hybrid electric vehicle (HEV) and the
electric vehicle (EV). In heating applications, as the heating load is reduced the fuel economy of the internal
combustion (IC) engine will be improved, the engine on time is reduced in the case of the HEV, and HV battery power consumption is reduced in the case of the EV.