Message Name:

[ACSC1-B] FWD DUCT OVERHEAT

Message Code:

2161517ECS

Associated CAS:

TRIM AIR FAIL
(Caution)

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

• Air Conditioning System Controller 1 (A87)
• Duct Temperature Sensor (DTS) 1 (E21)
• Forward Ventilated Temperature Sensor (B15)
• Forward Trim Air Valve (TAV) (L18)
• 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 FWD 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 forward TAV with aft TAV.

   1. If system checks are good, replace forward 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 forward 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 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 forward 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 forward 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. Interchange DTS 1 with DTS 2.

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

13. Interchange forward vent sensor with aft vent sensor.

    1. If system checks are good, replace forward 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.