62 DO THE APU USUAL SHUTDOWN (AMM 49-11-00/201).
REPLACE THE APU (AMM 49-11-00/401).
DO THIS TASK: REMOVAL OF OIL CONTAMINATION FROM THE AIRCONDITIONING AND PNEUMATIC SYSTEM (AMM 21-00-01/201)
Fumes or Smoke in the Cabin
Figure 129 (Sheet 3)

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
H85214
////////////////////////A / GTCP85-129 SERIES /737-300/400/500/ ENGINES /MAINTENANCE MANUAL ////////////////////////
PREREQUISITES 
MAKE SURE THESE CIRCUIT BREAKERS ARE CLOSED:
 P6-4 - D11
"DUAL BLEED" LIGHT  P6-5 - B1,B2,B5
IS ON WITH THE "APU  APU CONTROL UNIT 
BLEED" SWITCH IN THE  MAKE SURE THE AIRPLANE IS IN THIS CONFIGURATION: 
"OFF" POSITION  ELECTRICAL POWER IS ON (AMM 24-22-00/201) 

POSSIBLE CAUSES:
1.
APU CONTROL UNIT, M280, PROBLEM (AMM 49-61-11/401)

2.
BLEED AIR VALVE, V56, PROBLEM (AMM 49-52-11/401)

3.
POSITION INDICATING SWITCH FOR THE BLEED AIR VALVE PROBLEM (AMM 49-52-11/401).

_______________FAULT ISOLATION: 
1  OPEN THE CIRCUIT BREAKER  YES 51  REPLACE THE APU CONTROL 
ON THE APU CONTROL UNIT AND  UNIT, M280 (AMM 49-61-11/401). 
LIGHT GO OFF? DID THE "DUAL BLEED" BREAKER. THEN CLOSE THE CIRCUIT  ____NOTE:  CORRECT THIS PROBLEM. THE -31 APU CONTROL MODIFICATION "B" WILL UNIT WITH THE 

THE -64 OR -67 APU CONTROL UNIT WITH THE MODIFICATION "A" WILL CORRECT THIS PROBLEM.
NO NO

2 DISCONNECT CONNECTORS
D1450 AND D474 FROM THE APU
BLEED VALVE, V56.

DO A CONTINUITY CHECK ATTHE POSITION INDICATING SWITCHON THE BLEED AIR VALVE, V56,CONNECTOR D1450, PINS B AND C (WDM 49-31-01).
IS THERE AN OPEN CIRCUIT?
YES NO

3 MAKE SURE THE "APU BLEED"

53 REPAIR THE PROBLEMS THAT SWITCH, ON THE P5 FORWARD YOU FIND. OVERHEAD PANEL, IS IN THE IF NECESSARY, REPAIR THE "OFF" POSITION. CIRCUIT FROM THE POSITION
 DO A CONTINUITY CHECK FROM INDICATING SWITCH ON THE BLEED THE BLEED AIR VALVE, V56, AIR VALVE, V56, CONNECTOR CONNECTOR D474, PIN B, TO D1450, PIN B, TO THE AIR GROUND (WDM 49-31-01). CONDITIONING MODULE, P5-10,
IS THERE AN OPEN CIRCUIT?  CONNECTOR D646, PIN 44, AND CONNECTOR D680, PIN 44, FOR A
YES
SHORT TO GROUND
(WDM 21-62-01; 49-31-01).

DUAL BLEED Light Is On With the APU BLEED Switch in the OFF Position
Figure 130

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
F42246
EGT IS LESS THAN  PREREQUISITES 
620`C WITH BOTH AIR  MAKE SURE THIS SYSTEM WILL OPERATE: 
CONDITIONING PACKS IN  APU (AMM 49-11-00/201) 
THE "ON" POSITION 

POSSIBLE CAUSES:
1.
CLOGGING OF THE FILTER FOR THE DIFFERENTIAL PRESSURE REGULATOR (AMM 49-52-21/401)

2.
BLEED AIR VALVE, V56, PROBLEM (AMM 49-52-11/401)

3.
APU CONTROL THERMOSTAT PROBLEM (AMM 49-52-32/401).

FAULT ISOLATION:
YES

1 DO A CHECK OF THE FILTER
51 REPLACE THE DIFFERENTIAL FOR THE DIFFERENTIAL PRESSURE PRESSURE REGULATOR
REGULATOR (AMM 49-52-21/301). (AMM 49-52-21/401).
IS THE FILTER CLOGGED?

NO NO
2 REPLACE THE BLEED AIR
VALVE, V56 (AMM 49-52-11/
401).
START AND OPERATE THE APU(AMM 49-11-00/201).

DOES THE PROBLEM CONTINUE?

(AMM 49-11-00/201).
 REPLACE THE APU CONTROL THERMOSTAT (AMM 49-52-32/401).
EGT Is Less Than 620`C with Both Air Conditioning Packs in the ON Position Figure 131
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