TM 55-1510-219-10
and the cabin temp mode selector switch for selecting
automatic heating or cooling or manual heating or
cooling. Four additional manual controls on the main
instrument subpanels may be utilized for partial
regulation of cockpit comfort when the cockpit curtain is
closed and the cabin comfort level is satisfactory.
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 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.
Defrost air knob In as required.
3.
Overhead
cockpit
outlets
As
required.
(2)
If the cockpit is too hot:
1.
Pilot and copilot 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 temperature mode
selector 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 TM
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 provided the right engine N1 speed is above
62°. When the bypass valve is opened to a position
approximately 30° from full closed, the refrigeration
system will turn off.
(2)
The CABIN TEMP INCR control provides
regulation of the temperature level in the automatic
mode. A temperature sensing unit in the cabin, in
conjunction with the control setting, initiates a heat or
cool command to the temperature controller for desired
cockpit and cabin environment.
d.
Manual Mode Control. With the cabin
temperature mode selector in the MAN HEAT or MAN
COOL position, regulation of the cabin temperature is
accomplished manually with the MANUAL TEMP switch.
(1)
In the MAN HEAT mode, the automatic
system is overridden and the system is controlled by
opening and closing the bypass valves (two) with the
MANUAL TEMP INCR DECR switch. To increase cabin
temperature, hold the switch at the INCR position, to
decrease cabin temperature, hold the switch in the
DECR position. Allow approximately 30 seconds per
valve to drive the bypass valves to the fully open or fully
closed position. Only one valve moves at a time.
(2)
With the cabin temperature selector
switch in the MAN COOL position, the automatic
temperature control system is bypassed. In the manual
cooling mode, the refrigeration system is on, providing
the right engine right engine N1speed is above 62%,
however, the bypass valves may be manually positioned
for the desired temperature. Hold the MANUAL TEMP
switch in the DECR position approximately one minute
to fully close air-to-air heat exchanger bypass valves.
e.
Bleed Air and Vent Control.
(1)
Bleed air entering the cabin is controlled
by bleed air valve switches placarded BLEED AIR
VALVE OPEN ENVIRO OFF PNUE & ENVIRO OFF.
When the switch is in the OPEN position, the
environmental flow control unit and the pneumatic valve
are open. When the switch is in the ENVIRO OFF
position, the environmental flow control unit is closed
and the pneumatic bleed air valve is open; in the PNEU
& ENVIRO OFF position, both are closed. For
maximum cooling on the
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