TM 55-1510-222-1'0
control panel (fig. 2-13) provides for automatic or
manual control of the system. This section contains all
the major controls of the environmental function
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 - 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
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 N1 speed is above 65%. When the bypass valve
is opened to a position approximately 30° from full open,
the refrigeration system will turn off.
(2)
The CABIN AIR 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 in 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. When the left
bypass valve reaches a fully closed position, the
refrigeration system will begin cooling, provided the right
engine N1 speed is above 65%. When the bypass valve
is opened to a position approximately 30° from full open,
the refrigeration system will turn off. Hold the MANUAL
TEMP switch in the DECR position approximately one
minute to fully close air-to-air heat exchanger bypass
valves.
(3)
Bleed air entering the cabin is controlled
2-61
