Lexus 2003 LS Owner's Manual page 206

AIR CONDITIONING
The sensitivity of the sensor can be adjusted only while the
vehicle has stopped.
21L108
When you push either side of the "TEMP" button several times,
the sensitivity changes from "+3" down to "–3". If you do not
operate any button for a few seconds, the previous display
returns.
If manual on–off of the air conditioning is desired –
Push the "A/C" button to turn the air conditioning on and push
it again to turn the air conditioning off. If you turn off the air
conditioning manually, the EXHAUST GAS AUTOMATIC
mode will be cancelled.
If the outside temperature is lowered down to around 0BC
(32BF), the air conditioning will turn off automatically. At this
time, the indicator on the A/C button is off and the EXHAUST
GAS AUTOMATIC indicator light remains on. However, the
EXHAUST GAS AUTOMATIC mode does not operate. When
the air conditioning turns on as with the raised temperature, the
EXHAUST GAS AUTOMATIC mode resumes.
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If the system is used for ventilation, heating in dry weather or
removing frost or exterior fog on the windshield, turn the air
conditioning off once it is no longer required. This will improve
fuel economy. The air conditioning can be used for year–round
automatic temperature control including cooling and
dehumidifying operation.
If the air conditioning compressor does not operate, the
indicator of the "A/C" button will blink. If the indicator of the
"A/C" button blinks even when the "A/C" button is pushed
again, have the compressor checked by your nearest Lexus
dealer.