2. 3. 4. 5. 6. 7. 8. 9. 10. Cabin  temperature  mode  selector  switch  - AUTO. Cabin  temperature  control  rheostat  -  Full decrease. Vent blower switch - HI. Cabin  temperature  mode  selector  switch  - MAN  COOL. Manual  temperature  switch  -  DECREASE (hold). Left bleed air valve switch - ENVIRO OFF. If the light is still illuminated after 30 sec- onds:  Left  bleed  air  valve  switch  -  OPEN. Right  bleed  air  valve  switch  -  ENVIRO OFF. If the light is still illuminated after 30 sec- onds: Right bleed air valve switch - OPEN. NOTE If  the  overtemperature  light  has  not  extin- guished after completing the above proce- dure,  the  warning  system  has  malfunc- tioned. 9-11. ICE VANE FAILURE. Ice vane failure is indicated by #1 VANE FAIL or #2 VANE FAIL caution annunciator light illumi- nation.  If  an  ice  vane  fails  to  operate  electrically, perform the following: After  the  ice  vanes  have  been  manually extended,  they  must  be  mechanically retracted.  No  electrical  extension  or retraction shall be attempted as damage to the electric actuator may result. Link- age in the nacelle area must be reset prior to operation of the electric system. Do not reset ice vane control circuit breaker. Do not retract ice vanes electrically after manual  extension. 1. Airspeed - 160 KIAS or below. 2. Ice vane control circuit breaker - Pull. TM  55-1510-221-10 3. Ice vane - Operate manually. 4. Airspeed - Resume normal airspeed. 9-12. ENGINE BLEED AIR SYSTEM FAILURE. a. Bleed Air Failure Light Illuminated. Steady illumination of the warning light in flight indicates a possible ruptured bleed air line aft of the engine firewall.  The  light  will  remain  illuminated  for  the remainder of flight. Perform the following: NOTE L BL AIR FAIL or R BL AIR FAIL lights may momentarily illuminate  during simultaneous  surface  deice  and  brake deice operation at low N1 speeds. 1. Brake deice - OFF. 2. TGT and torque - Monitor (note read- ings). 3.  Bleed  air  valve  switch  -  PNEU  & ENVIRO  OFF. NOTE Brake deice on the affected side, and rud- der boost, will not be available with bleed air  valve  switch  in  PNEU  &  ENVIRO OFF. 4.  Cabin  pressurization  -  Check. b. Excessive Differential Pressure. If cabin dif- ferential pressure exceeds 6.1 PSI, perform the fol- lowing: 1. Cabin  altitude  and  rate-of-climb  con- troller  -Select  higher  setting. If   condition   persists:   LEFT   BLEED AIR  VALVE  switch  -  ENVIRO  OFF (light  illuminated). 2. 3. 4. 5. 6. If  condition  still  persists:  RIGHT BLEED AIR VALVE switch - ENVIRO OFF (light illuminated). If   condition   still   persists   -   Descend immediately. If  unable  to  descend:  CABIN  PRESS DUMP switch -CABIN PRESS DUMP. Bleed  air  valve  switches  -  OPEN,  if cabin heating is required. 9-7