(5)  
If the forward cargo compartment fire switch on the aft pilot's control stand P8 panel is ARMED, all power is interrupted to the heating flow fan.

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A 757 MAINTENANCE MANUAL

CONTROL MODULE

Forward Cargo Heating System Schematic
Figure 2 (Sheet 1)

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A

757
MAINTENANCE MANUAL

 B. Control
_______
 (1)  The forward cargo compartment heating system is a self controlled system requiring no pilot or mechanic action to place it into operation.
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A
757 MAINTENANCE MANUAL
 FORWARD CARGO COMPARTMENT HEATING SYSTEM - ADJUSTMENT/TEST
__________________________________________________________
 1.  General_______
 A.  This procedure contains two tasks. The first task is an operational test of the heating system in the forward cargo compartment. The second task is a system test of the heating system in the forward cargo compartment.
 B.  The heating system in the forward cargo compartment uses a thermal switch temperature control. When the temperature in the forward cargo compartment is less than 50°F (10°), the switch closes and sends a signal to a relay. The relay controls the heater fan. When the temperature in the forward cargo compartment is 70°F (21°C), the switch disconnects the circuit to the forward cargo compartment fan relay. This stops the heat supply to the compartment.
 TASK 21-43-00-715-002
 2.  Operational Test - Forward Cargo Compartment Heating System____________________________________________________________
 A.  General
 (1)  
This test makes sure the fan and temperature control switch operate correctly.

 B.  
Equipment

 (1)  
Cooling source - ice pack - commercially
 available

 (2)  
Thermometer - range 0 to 120°F (0 to 49°C) -commercially available

 C.  
References

 (1)  
AMM 24-22-00/201, Electrical Power Control

 D.  
Access

 (1)  
Location Zones
 121/122 Forward Cargo Compartment
 211 212 Control Cabin - Section 41

 E.  
Procedure

 (1)  
Supply electrical power (AMM 24-22-00/201).

 S 865-004

 (2)  
Make sure these circuit breakers on the pilot's overhead circuit breaker panel, P11, are closed:

 (a)  
11N1, INSTRUMENT AND PANEL AISLE STAND

 (b)  
11N17, CARGO HEATER FAN FWD

 (c)  
11S15, AIR/GND SYS 1

 (d)  
11S19, AIR/GND SYS 2

 S 865-003
 S 865-006
 (3)  
Make sure this circuit breaker on the miscellaneous electrical equipment panel, P70, is closed:
　
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