# SDR ASAA2015082312876

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: August 23, 2015
- Submitted: August 25, 2015
- Operation: Air carrier
- Aircraft: [N407AS](https://openairdocs.org/aircraft/N407AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 41731
- Aircraft time: 10,995 hours, 3,484 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Modulating Valve
- Part number: 3989084
- Part serial: 18503
- Condition: Failed
- Location: Nr 1 A/C Pack
- Part time: 10,984 hours, 3,480 cycles
- Stage of operation: NR
- How discovered: 9
- Nature of condition: O
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2015082312876

## Discrepancy

RIGHT AFT CABIN TEMP UNCONTROLLABLE.  ACFT GROUNDED.  NR 1 CONTROLLER SHOWS AFT CABIN TEMP CONTROL TRIM VALVE FAIL.  FOUND CONT CAB, FWD, AFT TEMP SENSORS CLOGGED. CLEANED SENSORS, NO HELP; AFT CABIN DRIVES TO FULL HOT.  REPLACED RT AFT CABIN ZONE TRIM AIR MODULATING VALVE REF AMM 21-61-21-000-801 AND 21-61-21-400-801. BIT CHECKS GOOD, LEAK CHECK GOOD. ZONE TEMP CONTROL OPS NORMAL REF 21-61-00.

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