two pictures attached showing the direction of air flow. There is a flap situated above the heater matrix - if the control is set in the cold position the flap drops and prevents the air flow passing through the matrix
Cold air direction in blue.
if the control is set in the hot position the flap is in the up right position, allows the air to pass through the matrix thus hot air and blocks the direction of the cold air.
Hot air direction in red.
Also there is a flap at the bottom of the housing which opens or closes - if screen is selected the flap is closed and no hot air goes to the footwells. Screen and car selected heat goes to both.
The flow of air alters is direction when ever an increase or decrease in temperature is selected.
Hope my explanation is understood.
Paul
