Temperature Mixing

IHKR E36 TEMPERATURE MIXING







IHKR E36 also offers the stratified air feature and, while inputs are the same, the components used to provide the feature are different than those used on IHKR E34.
- On E36 vehicles, the mixing flap control thumbwheel is located just below the center face vent, next to the shutoff valve thumbwheel.
- IHKR E36 uses a single stepper motor to operate a combined face vent/mixing flap mechanism.
- Air distribution knob position determines whether or not stratified air is available.

When the air distribution knob is positioned between about 7 o'clock and 1 o'clock, the control module runs the face vent/mixing flap stepper motor to its end stop. The main flap drops down, closing off the area between the evaporator and the heater cores. Also, as the motor reaches its end stop linkage pulls down an arm which forces a flap directly above the heater core to close.







With the flaps in these positions, all air is forced to pass through the heater cores, and it flows to the footwells or defroster outlets in a proportion that depends upon air distribution knob position. No air can flow upward, out of the housing, to the face vents.







When the knob is positioned between about 1 o'clock and 7 o'clock, the control module runs the face vent/mixing flap stepper motor in the other direction. The linkage moves just enough to lift the arm that is holding the door above the heater cores closed. With the door now open, heated air can flow up through the housing and out the face vents.

And, since the main flap is lifted to a position dependent upon thumbwheel position, air that has just passed through the evaporator can bypass the heater core, also flowing up through the housing and out the face vents.