(2)  
Two automatic pack-temperature controllers

 (3)  
One standby pack-temperature controller

 (4)  
Two flow control cards

 (5)  
Two flow-control-and-shutoff valves

 (6)  
Two pack-outlet overheat switches

 (7)  
Two cabin-air-supply check valves

 (8)  
Two altitude switches.

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MAINTENANCE MANUAL

LEFT PACK SEE A ECS BAY ACCESS DOORS
ACCESS 
DOORS 
TEMPERATURE 
CONTROL VALVE 
FLOW CONTROL AND 
SHUTOFF VALVE 
RAM AIR 
INLET DOOR 
RAM AIR DOOR 
ACTUATOR 
PACK ALTITUDE 
SWITCH (LEFT  CABIN AIR SUPPLY 
SIDE ONLY)  CHECK VALVE  FWD 
LEFT PACK SHOWN 
(RIGHT PACK SIMILAR) 
A 
Cooling Pack 
Figure 1 

MAIN LANDING GEAR DOORS
RAM AIR EXHAUST DOOR ACTUATOR
RAM AIR EXHAUST DOOR
LOW LIMIT
CONTROL VALVE

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MAINTENANCE MANUAL

PRIMARY HEAT 
EXCHANGER 
PLENUM/DIFFUSER  SECONDARY HEAT 
ASSEMBLY  EXCHANGER 
AIR CYCLE 
MACHINE (ACM) 
LOW LIMIT 
CONTROL 
VALVE 
CONDENSER 
RAM AIR 
INLET DUCT 
COMPRESSOR OUTLET 
PACK  SENSOR (2 PLACES) 
OVERHEAT 
SWITCH  WATER SPRAY NOZZLE 
COMPRESSOR OUTLET 
OVERHEAT SWITCH 
WATER  REHEATER  SPLIT-DUCT WATER 
EXTRACTOR  SEPARATOR 
PACK TEMPERATURE 
SENSOR (2 PLACES) 
FWD 
LEFT PACK SHOWN 
(RIGHT PACK SIMILAR) 
Cooling Pack Components 
Figure 2

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MAINTENANCE MANUAL

 D.  Most of the components in the cooling pack system are interchangeable between the left and right systems. The only component that is not interchangeable is the standby pack temperature controller, because there is only one of them on the airplane.
 E.  The air cooling packs are installed in the left and right environmental control system (ECS) bays. The ECS bays are under the airplane wings, immediately forward of the main landing-gear wheel wells.
 2.  Component Details_________________
 A.  Flow Control and Shutoff Valve (Fig. 3, 4)
______________________________
 (1)  
The flow-control-and-shutoff valve lets a controlled amount of air flow from the pneumatic system into the air cooling pack. There are two valves, one for each air cooling pack. Each valve is installed forward and outboard of its air cooling pack.

 (2)  
The flow-control-and-shutoff valve lets air into the air cooling pack at two different flow rates. Usually, each valve lets approximately 72 pounds (24 cubic meters) per minute of air into each pack. In the "high flow mode", this rate increases to between 105 pounds (39 cubic meters) and 117 pounds (44 cubic meters) per minute. This is a 65 percent increase for the cooling pack. It also means that one cooling pack can supply about 80 percent of the air that is usually supplied by two cooling packs.

 (3)  
The flow-control-and-shutoff valve is a venturi-type, butterfly valve. It is electrically controlled and pneumatically operated. It is approximately 4 inches in diameter, 14 inches in length, and weighs 10.5 pounds.
　
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