TM 1-1510-223-10
(3) Air conditioning cold operation mode. (Used
if ambient temperature is between 10°C and -25°C).
NOTE
Setting the cabin temperature mode selector
switch to the AC COLD OPN position at ambient
temperatures below -25°C may cause the air
conditioning system to exceed the compressor
low
pressure
limit
setting,
terminating
compressor operation, and thereby rendering the
system inoperative for the remainder of the flight
1.
BLEED AIR valve switches - ON, LEFT
and RIGHT.
2.
CABIN AIR MODE SELECT switch - AC
COLD OPN.
3.
CABIN AIR TEMP CONTROL rheostat -
As required.
4.
CABIN, PILOT, COPILOT, and
DEFROST
air
knobs
-
As
required.
2-70.
UNPRESSURIZED VENTILATION.
Ventilation is provided by two sources. One source is
through the bleed air heating system in both the
pressurized and unpressurized mode. The second source
of ventilation is obtained from ram air through the
condenser section in the nose through a check valve in
the vent blower plenum. Ventilation from this source is in
the unpressurized mode only with the CABIN PRESS
DUMP switch in the DUMP position. The check valve
closes during pressurized operation. Ram air ventilation
is distributed through the main ducting system to all
outlets. Ventilation air, ducted to each individual eyeball
cold air outlet, can be directionally controlled by moving
the ball in the socket Volume is regulated by twisting the
outlet to open or close the valve.
2-71.
ENVIRONMENTAL CONTROLS.
An environmental control section on' the overhead
control panel (fig. 2-13) provides for automatic or manual
control of the system. This section contains all the major
controls of the environmental system including bleed air
valve switches, forward and aft vent blower switches,
manual temperature switch for control of the heat
exchanger valves, a cabin temperature level control, and
the cabin temperature mode selector switch for selecting
automatic heating/ cooling or manual heating/cooling.
a.
Heating Mode.
(1) If the cockpit is too cold:
1.
PILOT and COPILOT AIR knobs - As
required.
2.
DEFROST AIR knob - As required.
3.
CABIN AIR knob - Pull out in small
increments. Allow 3 to 5 minutes
after
each
adjustment
for
system to stabilize.
(2) If the cockpit is too hot:
1.
CABIN AIR knob - As required.
2.
PILOT and COPILOT AIR knobs - In as
required.
3.
DEFROST AIR knob - In as required.
b.
Cooling Mode:
(1) If the cockpit is too cold:
1.
PILOT and COPILOT AIR knob - In as
required.
2.
DEFRIST AIR knob - In as required
3.
Overhead cockpit outlets - As required.
(2) If the cockpit is too hot:
1.
PILOT and C(OPILOT AIR knobs - Out as
required.
2.
CABIN AIR knob - Close in small
increments. Allow 3 - 5 minutes
after
each
adjustment
for
system to stabilize.
If
CABIN AIR knob is completely closed
before obtaining satisfactory cockpit
comfort, it may be necessary to place the
AFT VENT BLOWER switch in the ON
position to activate the aft evaporator to
recirculate cabin air.
c.
Automatic Mode Control. When the AUTO mode
is selected on the CABIN AIR MODE SELECT switch, the
heating and air conditioning systems are automatically
controlled. When the temperature of the cabin has
reached the selected setting, the automatic temperature
control allows heated air to bypass the air-to-air
exchangers in the wing center section. The warm bleed
air is mixed with the cooled air. The rear evaporator picks
up recirculated cabin air only.
(1) When the automatic control drives the
environmental system from a heat mode to a cooling
mode, the bypass valves close. When the left bypass
valve reaches a fully closed position, the refrigeration
system will begin cooling, provided the right engine N,
speed is above 650a When the bypass valve is opened to
a position approximately 30°
from full open, the
refrigeration system will turn off.
2-62
