US Patent 7793706 HVAC dual zone temperature control with slave rear zone

An HVAC assembly including an HVAC case disposed in a passenger compartment of a vehicle includes a first air mix door. The first air mix door is movable between open and closed positions and adapted to adjust a temperature of air blown into a front passenger compartment. A second air mix door is movable between open and closed positions and adapted to adjust a temperature of air blown into a rear passenger compartment. The HVAC assembly further includes a motor and a mechanical linkage operably coupling the motor with the first and second air mix door whereby movement of the motor corresponds to movement of both the first and second air mix doors.