Lexus GX470 2004 Owner's Manual page 259

AIR CONDITIONING
You can adjust the temperature within "10_F ("5_C)
which compared with the temperature setting of the front
air conditioning. Push the left side of the button to lower
the temperature, and push the right side to raise the
temperature.
NOTICE
To prevent the battery from being discharged, do not
leave the rear cooler on longer than necessary when the
engine is not running.
242