TM 1-1510-224-10 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. 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 and 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. 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 65%.    When  the  bypass  valve  is  opened  to  a  position approximately    30     from     full     open,     the     refrigeration system will turn off. The  CABIN  AIR  TEMP  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   AIR MODE   SELECT   switch   in   the   MAN   HEAT   or   MAN COOL  position,  regulation  of  the  cabin  temperature  is accomplished  manually  with  the    CABIN  AIR  MANUAL TEMP switch. (1) In the   MAN   HEAT   mode,   the   automatic system   is   overridden   and   the   system   is   controlled   by opening  and  closing  the  bleed  air  bypass  valves  (two) CABIN AIR MANUAL TEMP - INCREASE - DECREASE   switch.      To   increase   cabin   temperature, hold the switch in the   INCREASE  position;  to  decrease cabin  temperature,  hold  the  switch  in  the    DECREASE 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   AIR   MODE   SELECT 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 N, 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    CABIN AIR MANUAL TEMP switch in  DECREASE  position  for approximately   one   minute   to   fully   close   air-to-air   heat exchanger bypass valves. (3) Bleed  air  entering  the  cabin  is  controlled by  LEFT and  RIGHT  bleed  air  valve  switches  placarded ENVIRO  &  PNEU  BLEED  AIR  -  PNEU  ONLY  -  ON. When the switch is in the  ON position, the environmental flow   control   unit   and   the   pneumatic   valve   are   open. When   the   switch   is   in   the   PNEU   ONLY   position,   the environmental     flow     control     unit     is     closed     and     the pneumatic  bleed  air  valve  is  open.    In  the    ENVIRO  & PNEU   BLEED   AIR   position,    both    are    closed.        For maximum cooling on the ground, turn the bleed air valve switches to the PNEU ONLY position. (4) The   forward   vent   blower   is   controlled   by the switch placarded   VENT  BLOWER  FWD  -  AUTO  - LOW  -  HIGH.    The   HIGH and   LOW  positions   regulate the  blower  to  two  speeds  of  operation.    In  the     AUTO position,  the  fan  will  run  at  low  speed  except  when  the 2-71