Cadillac CTS-V 2009 Owner's Manual page 174

The outboard air outlets always receive some airflow in
every mode, except defrost.
To change the current mode, select one of the following:
Y
(Vent): Air is directed to the instrument panel outlets.
\
(Bi-Level): Air is divided between the instrument
panel outlets and the floor outlets. In automatic
operation, cooler air is directed to the upper outlets
and warmer air to the floor outlets.
[
(Floor): Air is directed to the floor outlets, with
some air directed to the windshield and outboard outlets.
-
(Defog): This mode clears the windows of fog or
moisture. Air is directed to the windshield, floor and side
window outlets. When this mode is selected, the system
turns off recirculation and runs the air-conditioning
compressor unless the outside temperature is at or below
freezing. If recirculation is selected while in defog mode,
it is cancelled after 10 minutes.
3-26
0
(Defrost): This mode clears the windshield of fog
or frost more quickly. Air is directed to the windshield,
with some air directed to the side windows. In this mode,
the system automatically turns off recirculation and runs
the air-conditioning compressor, unless the outside
temperature is at or below freezing.
This mode can also cause the fan speed and air
temperature to increase.
#
(Air Conditioning): Press to turn the air conditioning
system on or off and override the automatic system.
When in AUTO, the air conditioning compressor comes
on automatically, as needed.
The air conditioning system removes moisture from
the air, so a small amount of water might drip under the
vehicle while idling or after turning off the engine.
This is normal.