Ford F series Owner's Manual page 61

Airflow selections
VENT
Use VENT to bring outside air through the
instrument panel registers. You can heat the air
in this position by rotating the center knob into
the RED area. The air CANNOT be cooled
below the outside temperature regardless of the
center knob setting. Select NORM A/C or MAX
A/C to get cool air through the instrument
panel registers.
NORM A/C (If equipped)
Select NORM A/C to get refrigerated outside air
through the instrument panel registers. The A/C
position is used for cooling except when it is
extremely hot or fast cooling of the vehicle is
needed. Then, select MAX A/C for fast cooling
and return to NORM A/C when you are
comfortable.
MAX A/C (If equipped)
The MAX A/C position produces cool air more
rapidly to provide faster cooling of your vehicle.
This is possible because cooler air is drawn from
inside the passenger area and refrigerated again
instead of using warmer outside air. Using
inside air will also make the fan sound louder
which is normal when using MAX A/C. The air
flow will be from the instrument panel registers.
FLOOR
Air flow will be to the floor when FLOOR is
selected. The air cannot be cooled in the FLOOR
position but can be heated by rotating the center
knob in the RED area.
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