# SDR ASAA2021072635532

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: July 26, 2021
- Submitted: July 28, 2021
- Operation: Air carrier
- Aircraft: [N477AS](https://openairdocs.org/aircraft/N477AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 40716
- Aircraft time: 21,864 hours, 6,851 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Sensor
- Condition: Dirty
- Location: Cockpit Temp
- Stage of operation: NR
- How discovered: O
- Nature of condition: N
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2021072635532

## Discrepancy

CONT CABIN 'ZONE TEMP' ILLUMINATES ON RECALL AND EXTINGUISHES WITH MASTER CAUTION RESET. GROUNDED - YES. PACK/ZONE TEMP CONTROLLER BITE PER B737-900 FIM 21-62 TASK 801 SHOWED FAULT FOR CONTROL CABIN TEMP CONTROL VALVE BUT VERIFY TEST DID NOT CONFIRM FAULT. FOUND CONTROL CABIN TEMP SENSOR AND FILTER DIRTY - CLEANED SENSOR AND REPLACED FILTER. PERFORMED CABIN TEMP CONTROL AND INDICATION OPERATIONAL TEST PER B737-900 AMM 21-61-00-700-807-002 AND PZTC BITE PER ABOVE FIM - ALL TESTS PASS.

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