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A
757 MAINTENANCE MANUAL 
AIR CONDITIONING
CONTROL MODULE 
P11 PANEL
SEE A 
P5 PANEL 
P61 PANEL 
FLIGHT COMPT
AIR CONDITIONING CONTROL MODULE 
A 
Recirculation System 
Figure 1 (Sheet 1)
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757 
MAINTENANCE MANUAL
RECIRCULATION  RECIRCULATIONSEE B 
AIR FAN AIR CHECK VALVE SEED SEEF 
SEE  C  
RECIRCULATION  
AIR CHECK VALVE  FILTERS  
RECIRCULATION  SEE  F  SEE  E  FILTER SUPPORT  
AIR FAN  
SEE  G 
MIX MANIFOLD  
B  MIX  
MANIFOLD  
FILTER  
SUPPORT  
FILTERS  
SEE  E  
ELECTRICAL  
CONNECTION  
C  RIGHT RECIRCULATION AIR FAN  
D 
INBD  
HIGH  
EFFICIENCY  
FILTER  PREFILTER  FWD  
RECIRCULATION AIR FILTERS  RECIRCULATION AIR CHECK VALVE  LEFT RECIRCULATION AIR FAN  
E  F  G 
Recirculation System 
Figure 1 (Sheet 2)
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MAINTENANCE MANUAL
 B.  Recirculation Air Filters
_________________________
 (1)  
Physical Description
 (a)  
A pre-filter and high efficiency particulate filter are both encased in an aluminum frame. The right recirculation filters mount to the right of the mix manifold at the rear of the forward cargo compartment, upstream of the fan. The left filter assembly mounts to the left and just upstream of the mix manifold. 1) Pre-filter
 a)  The pre-filter is a particulate filter. It contains an aluminum frame around a fiberglass pad. The 1.5 pound filter traps the largest of the contaminant particles. The pre-filter is rated at 1000 cpm airflow and has a minimum arrestance of 60%.
 2) High Efficiency Particulate (HEP) Filter
 a)  The HEP filter is a glass filter with an aluminum frame. The 3 pound filter, rated at 1000 cpm airflow, has a minimum arrestance of 95% for smoke particles 0.3 microns or larger.
 C.  Recirculation Air Check Valve
_____________________________
 (1)  
Physical Description
 (a)  
A recirculation air check valve is located just downstream of each recirculation fan. The check valve is 7 inches in diameter and contains a seat/flapper assembly, centered and riveted into the check valve housing. The seat/flapper assembly contains two semi-circular flappers hinged about a central pin. A stop pin provides a limit to prevent over-travel of the flappers.
 (2)  
Function
 (a)  
Airflow, in the direction of the arrow on the valve housing, opens the flappers until they come in contact with the stop pin. Reverse airflow closes the check valve flappers against the seat. This action prevents air from passing back through the system, into the cargo compartment and forward equipment center.
 3.  Operation (Fig. 2 and 3)
_________
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MAINTENANCE MANUAL
GROUND CONDITIONEDAIR CONNECTOR 
Right Recirculation Fan Operation SchematicFigure 2 
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