_________
 A.  Functional Description (Fig. 2)
 (1)  
Conditioned air flows to the compartment when the main distribution manifold is pressurized by the air conditioning packs or by conditioned air ground cart.

 (2)  
The captain and first officers windshield air shutoff valves are each controlled by separate heater and windshield air control modules. There is an ON/OFF switch labeled WSNLD AIR on each module. By setting the switch to ON, 28 volts dc is supplied to open the valve. With the switch set to OFF, 28 volts dc is supplied to close the valve.

 B.  Control
 (1)  
Supply conditioned air to the airplane by ground cart or air conditioning pack operation (Ref 21-00-00). This supplies conditioned air to the flight deck gaspers and diffusers.

 (2)  
Set the WSHLD AIR switch to ON. This supplies conditioned air to the front windshield.

 (3)  
To shut down the system remove the conditioned air source (Ref 21-00-00) and set the WSHLD AIR switch to OFF.

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A

747-400 MAINTENANCE MANUAL
FLIGHT COMPARTMENT

SHOULDER HEAT SWITCH

HEATER AND WINDSHIELD AIR CONTROL MODULE

Flight Compartment Condition Air Distribution Equipment Location
Figure 1 (Sheet 1)

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 ú  01  Page 2
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

MANUAL OVERRIDE/ POSITION INDICATOR (ON SOME VALVES)
WINDSHIELD AIR SHUTOFF VALVE
WINDSHIELD AIR SHUTOFF VALVE C
CLAMP  ELECTRICAL CONNECTOR
WINDSHIELD AIR
SHUTOFF VALVE

FWD
FWD
WINDSHIELD AIR SHUTOFF VALVE C
NOTE: DIFFERENT WINDSHIELD AIR SHUTOFF VALVES CAN BE INSTALLED. REFER TO IPC FOR APPLICABILITY.
Flight Compartment Condition Air Distribution Equipment Location Figure 1 (Sheet 2)
K30336
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A
747-400
MAINTENANCE MANUAL

Flight Compartment Condition Air Distribution Equipment Location
Figure 1 (Sheet 3)

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K30169
A

747-400
MAINTENANCE MANUAL

28V DC BUS WSHLD AIR

P180 DC POWERDISTRIBUTION PANEL

M7375 CAPT HEATER V464 CAPT WINDSHIELD CONTROL MODULE (P44) AIR SHUTOFF VALVE
Windshield Air Shutoff Valve Schematic
Figure 2

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A
747-400 MAINTENANCE MANUAL
 WINDSHIELD AIR SHUTOFF VALVE - REMOVAL/INSTALLATION
___________________________________________________
 1.  General_______
 A.  This procedure contains two tasks: removal and installation of a windshield air shutoff valve.
 B.  The steps that are necessary for removal of a windshield air shutoff valve are as follows:
　
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