# SDR ASAA2023020441858

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 4, 2023
- Submitted: February 8, 2023
- Operation: Air carrier
- Aircraft: [N563AS](https://openairdocs.org/aircraft/N563AS), registered now
- Make and model: Boeing 737890
- Aircraft serial: 35180
- Aircraft time: 58,472 hours, 17,216 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: None
- Condition: None
- Location: None
- Stage of operation: NR
- How discovered: V
- Nature of condition: J
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2023020441858

## Discrepancy

CONTROL CABIN ZONE TEMP LIGHT ILLUMINATES ON RECALL AND RESETS WITH MASTER CAUTION RESET. GROUNDED - YES.   SYSTEM HAD CONTROL CABIN TRIM MODULATING VALVE FAULT. IT RESET & SYS BITE PASSED BUT THERE IS A PREVIOUS WRITE UP LAST WEEK. SAME FAULT & RESET WITH NO LRU CHANGE. CONT CAB ZONE TEMP LT DOES NOT SHOW ON MASTER RECALL. PERFORMED PZTC BITE IAW FIM 21-62 TASK 801, NO FAULTS PRESENT ON EITHER CONTLR 1 OR 2, BIT, PREV, OR VERIFY, GREEN ON VERIFY, RESET X2. AS PRECAUTION, CLEANED FLT DECK TEMP SENSOR IAW AMM 21-61-10-100-801. FILTER WAS EXTRA DUSTY. PERFORMED CABIN CONT AND INDICATION OPS TEST IAW AMM 21-61-00-700-807-002. BOTH PACKS RAN INDEPENDENTLY AND TOGETHER, HIGH AND LO, NO OBSERVED DEFECTS.

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