Toyota Lexusc Owner's Handbook Manual page 308

When the windshield air flow button is pushed, air flows mainly
from the windshield vents and turns on the defrosting function
with the purpose of clearing the front view.
Pushing this button once again returns the air flow mode to the
last one used.
This button allows the air intake to select OUTSIDE AIR mode
automatically. This is to clean up the front view more quickly.
If you want to return the setting to RECIRCULATED AIR mode,
push the air intake control button once again.
Push the "A/C" button for dehumidified heating or cooling. This
setting clears the front view more quickly.
D To heat the vehicle interior while defrosting the windshield,
choose floor/windshield air flow.
AIR CONDITIONING
289