Cessna 172P - Page 231

PILOT'S OPER,ATING
HANDBOOK
SUPPLEMENT
2
AIR. CONDITIONING
SYSTEM
MODEL
172P
ds a
is uot
corl
or
at
less
used'
and without
the condenser
be conducted
without
flaPs
e.
With
the
condenserfairing
s,
the
speeds
on the
Takeoff
Distance chart
in
Section
5 of the basio handbook
and
a 10o flap
setting
may
be used. AII other speeds
remain
unchanged
from those
listed
in Section
4
of the basic handbook.
OPER,ATION IN
FT,IGHT
on of the
air
conditioning
system is
basically
the
ration. If fast
cool down
is desired,
check
that
all
the
AIR TEMP
control
in
the MAX
position,
and
place
the
FAN control
in the HI
position.
When
cabin
temperature
ha,s
been
reduced
to
the desired
level, rotate
the
AIR TEMP
control
knob counter-
clockwise
as required
to maintain
that
temperature and
reposition
the
FAN
control knob as dosired.
During
extended
flight
in extremely
high temperature
and humidity'
the evaporator coils may
frost over.
The evaporator
unit
is equipped
with
an automatic defrost system
which
will
normally
prevent
this.
However'
when
the AIR TEMP
control is
placed
in
the MA'X
position,
the automatic
defrost
system
will not operate.
This
problem
can be
recognized
by a
continual rise in
the
temperature
of the
airflow
from the outlets. To
correct
the
problem,
move the AIR TEMP control
knob approximately
one-third
of
the
way toward
ühe
OFF
position
and check
that the
FAN control knob
is
in
the HI
position.
This action should allow
the automatic
defrost system
to
remove
the
frost,
NOTE
If the temperature
of the air coming
from
the
outlets
does
not start
to cool within
a
reasonable
length of time
(depending
on
the a,mount of frost),
the system may be
malfunctioning
and should
be
turned off.
The
blower
portion
of the
system may be
used any time air
circulation
(heated
or fresh) is desired.
This is accomplished by
leaving
the
AIR TEMP
control
knob in the
OFF
position,
and
placing
the
FAN
control
knob
in the
LOW, MED,
or
HI
position
as desired.
BEFOR,E LANDING
1. AIR
TEMP Control Knob
--
OFF
5
30
May
1980