Message Name:

[ACSC1-B] AFT DUCT OVERHEAT

Message Code:

2162518ECS

Associated CAS:

TRIM AIR FAIL
(Caution)

The Aft Cabin Duct has been detected in overheat condition by the left Air Conditioning Controller (ACSC) 1.

• Air Conditioning System Controller 1 (A87)
• Duct Temperature Sensor (DTS) 2 (E22)
• Aft Ventilated Temperature Sensor (B16)
• Aft Trim Air Valve (TAV) (L19)
• Junction Box (JB5)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

1. Access CAIMS and check AFT DTS temperature reading. (CAIMS path: SYSTEM DIAG/AIR CONDITIONING/ACSC1A/LRU TEST/L ACSC CH. A TRIM & CABIN TEMP SENSOR DATA). It should change with cabin temp commands.

   1. If temp reading does not change, go to step 10.
   2. If temp reading change, continue with next step.

2. Select the Aux Press Switch (SDS7) from the Bleed Air Control Panel to ON and then to OFF. Make sure the forward TAV go full open and full close according to the switch position (refer to Air Conditioning synoptic page).
3. Interchange aft TAV with fwd TAV.

   1. If system checks are good, replace aft TAV and perform step 1 again.
   2. If fault remains, continue with next step.

4. Perform a wiring checks between Bleed Air Control Panel Aux Press Switch (SDS7) and JB5.

   1. If wiring checks are not good, repair the defective associated wiring and do close out.
   2. If wiring checks are good, continue with next step.

5. Perform continuity check of JB5.

   1. If there is no continuity, replace JB5 and do close out.
   2. If there is continuity, continue with next step.

6. Perform a wiring checks between JB5 and aft TAV including the ground.

   1. If wiring checks are not good, repair the defective associated wiring and do close out.
   2. If wiring checks are good, continue with next step.

7. Make sure power from SPDA 2 is received at JB5.
8. Perform a wiring checks between SPDA 2 and JB5 as follow:
   

   From	To	Result
   A14P4-C	JB5

   1. If wiring checks are not good, repair the defective associated wiring and do close out.
   2. If wiring checks are good, continue with next step.

9. Perform continuity check of JB5 as per a wiring checks.

   1. If there is no continuity, replace JB5 and do close out.
   2. If there is continuity, continue with next step.

10. Perform a wiring checks between ACSC 1 and aft duct temp sensor (DTS).

    1. If wiring checks are not good, repair the defective associated wiring and do close out.
    2. If wiring checks are good, continue with next step.

11. Perform a wiring checks between ACSC 1 and aft Vent Sensor.

    1. If wiring checks are not good, repair the defective associated wiring and do close out.
    2. If wiring checks are good, continue with next step.

12. Swap the DTS 2 with DTS 1.

    1. If system checks are good, replace DTS 2 and do close out.
    2. If fault remains, continue with next step.

13. Swap aft vent sensor with fwd vent sensor.

    1. If system checks are good, replace aft vent sensor and do close out.
    2. If fault remains, continue with next step.

14. Perform a wiring checks between ACSC 1 and JB5-K2.

    1. If wiring checks are not good, repair the defective associated wiring and do close out.
    2. If wiring checks are good, continue with next step.

15. Perform continuity check of JB5.

    1. If there is no continuity, replace JB5 and do close out.
    2. If there is continuity, continue with next step.

16. Replace ACSC 1.
17. Do close out.