Toyota Lexusc Owner's Handbook Manual page 296

AIR CONDITIONING
D The "Floor/Windshield" air flow mode may be applied
automatically, if the outside temperature is lowered
down to below 0 _ C (32 _ F).
This is not malfunction. The "Floor/Windshield" air
flow mode turns on the defogging and defrosting
function with the purpose of cleaning your front view
for safe driving.
If the "Floor" air flow mode is desired with the main
purpose of heating, "Floor" air flow mode can be
selected manually by pushing the "MODE" (air flow
control) button.
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