Cessna 402C Pilot Operating Handbook page 249

G".~·402C
MODEL
SECTION 7
AIRPLANE & SYSTEMS DESCRIPTIONS
Cabin heated air temperature can be increased during operation in cold
weather
by
pushing the ram air knob fully in. This will allow heated cabin
air to be recirculated through the heater, thus increasing heater capa-
bility. During extremely cold weather, manually adjust the defrost, for-
ward cabin and aft cabin air controls to reduce total airflow into the
cabin.
r--------NOTE - - - - - - - - - ,
elf
wann air is not COOling out of the registers
within one minute, turn cabin heat switch breaker
OFF; check and try another start.
If
heater still
does not start, no further starting attempt should
be made.
eDuring heater operation, the defrost and/or cabin
air knobs must be out.
eU.nder certain
flight conditions the, relative humid-
ity of the cabin air may increase to the point that
moisture (condensation) fonns on the inside of the
cabin windows. To control cabin window "fogging",
open the Ram Air vent (as required), to increase air
ventilation in the cabin.
HEATER USED FOR VENTILATION
(11
Battery Switch - ON.
~ 2 Cabin Air Knobs - PULL OUT.
3 Defrost Knob - PULL OUT.
4 Cabin Fan Switch - LO or HI as desired.
(5) Ram Air Knob - PULL OUT.
VENTILATING SYSTEM
During ground operation, ventilation is provided by the ventilating fan
of the cabin heat system or the optional circulation blower, if installed.
In flight ventilation, for airplanes without air conditioning installed,
is obtained through the ram air inlet located at the forward end of the
dorsal fin. This ram air is then distributed to the cabin via the overhead
directional air vents. On airplanes with optional air conditioning or
~ optional blower systems, a duct mounted internally in the dorsal fin,
activated by cam/microswitch butterfly valves, provides availability of
conditioned air or outside ram air, depending on cabin comfort reqUire-
ments.
OXYGEN SYSTEM
The oxygen system provides individual service for the pilot, copilot and
each passenger. The oxygen supply is stored in either two 22.0 cubic foot
or a 114.9 cubic foot bottle located in the nose compartment. Cabin plumb-
ing, including outlets for each occupant, is standard with each airplane
and will vary with individual airplane seating configuration. The oxygen
control, pressure gage (see Figure 7-1), bottle, regulator and nose com-
partment plumbing is optional.
1 November 1979
Revision 2 - 3 Aug 1981
7-45