Toyota Lexusc Owner's Handbook Manual page 291

AIR CONDITIONING
The automatic air conditioning automatically maintains
the set temperature.
In the automatic operation mode, the air conditioning selects
the most suitable fan speed, air flow, air intake and on-off the
air conditioning according to the temperature.
NOTICE
To prevent the battery from being discharged, do not
leave the air conditioning on longer than necessary
when the engine is not running.
272
The ignition key must be in the "ON" position.