Cadillac 1996 DeVille Owner's Manual page 150

If your vehicle is sitting out on a hot day and you have
it set -on AUTO, the air will first flow out the floor air
outlets for a few seconds. That is normal. This is to
expel hot air in the air outlets. As the air is cooled, the
aifflow will move through the A/C outlets. If you start
your vehicle with the fan setting on
HI,
it will skip the
A/C Purge.
To avoid blowing cold air in cold weather, the system
will delay turning on the fan until warm air is available.
The length of delay depends on the outside air
temperature, engine coolant temperature or the time
since the engine was last started. As the coolant warms
up, the blower fan speed will gradually increase and air
will flow from the heater outlets, with some aifflow to
the windshield to prevent fogging under most nonnal
conditions.
If you leave your vehicle, the system will remember the
control setting the next time you start your engine,
except for recirculation and defrost. Each ignition cycle
cancels recirculation, whereas, DEFROST will change
to AUTO when the ignition is shut off and then turned
back on.
Manual Operation
RECIRCULATION:
Press this button to limit the
amount of fresh air entering your vehicle. This is helpful
when you are trying to cool the air quickly or limit odor
entering your vehicle. In the AUTO mode, the system
will use recirculation as necessary to cool the air.
Pressing the recirculation button will change the
operation to a manual mode and the air will recirculate
non-stop. Press this button again to turn off the
recirculation feature.
If you notice the windows fogging, press the
recirculation button to exit the recirculation mode.
OFF: Press this button to turn the system off.
Fresh air will continue to flow through the vehicle,
and the system will try to maintain the previously set
temperature. The outside temperature will show in
the display when the system is off.
@
DE-ICE (Option): Pressing this button helps to
remove ice or frost from the windshield. See "Heated
Windshield" later in this section.