02/02/21
Message Overview:
Message Description:
The Cockpit Hot Air Regulating and Shut-off Valve (HARSOV1) is detected failed in CLOSED position.
Possible Causes:
- Cockpit Hot Air Regulating and Shut-off Valve (HARSOV1)
- Integrated Air System Computer (IASC 1) (A55)
- Junction Box 1 (JB1)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
HARSOV position can be monitored via IAC LRU Test Page
- Select IASC 2A and go to the Air Conditioning Raw Data Page
- Select Air Conditioning Valve Status to view HARSOV position
NOTE: Select "TRIM AIR ONLY" on the AIR COND / BLEED panel, the HARSOVs are fully open. HOT AIR REG SOV 1 and 2 should both go from FULL CLOSED/NOT FULL OPEN to NOT FULL CLOSED/FULL OPEN within 6 to 7 seconds.
Quick Links:
| Removal of the Integrated Air System (IAS) Controller | AMM 21-31-01-000-801 |
| Installation of the Integrated Air System (IAS) Controller | AMM 21-31-01-400-801 |
| Removal of the Hot-Air Regulating-and-Shutoff Valve | AMM 21-61-05-000-801 |
| Installation of the Hot-Air Regulating-and-Shutoff Valve | AMM 21-61-05-400-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
| Electrical Connectors - Maintenance Practice - ALL | SPM 20-20-00-02 |
Troubleshooting Recommendations:
- Do wiring check between IASC2, HARSOV1 and ground.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Swap HARSOVs.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Swap IASCs.
- Do close out.
