# SDR ASAA2021020534059

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 5, 2021
- Submitted: February 10, 2021
- Operation: Air carrier
- Aircraft: [N453AS](https://openairdocs.org/aircraft/N453AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 36354
- Aircraft time: 26,892 hours, 8,571 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Modulating Valve
- Part number: 3989085
- Part serial: 1582
- Condition: Faulted
- Location: Lt A/C Pack
- Part time: 78,592 hours, 37,121 cycles
- Stage of operation: NR
- How discovered: O
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2021020534059

## Discrepancy

CONT CAB ZONE TEMP LIGHT ILLUMINATES ON MASTER RECALL AND RESETS. GROUNDED - YES. ACCOMPLISHED B737-900 FIM 21-62 TASK 801. FOUND FLT DECK TRIM VALVE FAULT. REPLACED ZONE TRIM AIR MODULATING VALVE PER B737-900 AMM 21-61-21-401, OPERATIONAL CHECK GOOD. NO FAULTS FOUND. GROUND VERIFICATION SUCCESSFUL.

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