# SDR CALA2026010212585

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 29, 2025
- Submitted: January 2, 2026
- Operation: Air carrier
- Aircraft: [N27253](https://openairdocs.org/aircraft/N27253), registered now
- Make and model: Boeing 737-8
- Registry model: [Boeing 737-8](https://openairdocs.org/model/boeing-737-8) (OpenAirDocs)
- Aircraft serial: 43930
- Aircraft time: 15,784 hours, 5,518 cycles
- System (JASC): [2150 · Cabin Cooling System](https://openairdocs.org/jasc/2150)
- Part: Valve
- Part number: 632920704
- Part serial: 2106
- Condition: Faulted
- Location: Zone 100
- Stage of operation: CR
- 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/CALA2026010212585

## Discrepancy

FLIGHT DECK BECAME VERY COLD. LT PACK SHOWING 0 DEGREES. EMER PROC PERFORMED.CREW DEBREIF. CREW REPORTS SEVERSLMHOURS AT CRUISE NOTICED FLT DECK GETTING COLDER, ATTEMPTED TO INCREASE TEMP THROUGHNTEMP CONTROL DIALS WITH NO CHANGE. FOLLOWED QRH DIRECTION TO CHECK TEMP OUTPUT & FOUND LT PACK TEMP READING 0 & RT PACK IN MID 20'S. TURNED LT PACK OFF & FOUND TEMP STABILIZED BUT NOT INCREASING. DURING DECEMT AT APROX FL19000 PILOTS REPORT SMEELING HEAT & THEN TEMP RAPIDLY INCREASED WITH LT PACK STILL OFF. CREW DEBRIFF CONT.  CREW REPORTED THAT CABIN TEMP FOR PASSENGERS STAYED COMFORTABLE BUT WAS BEGINNING TO DECLINE WITH JUST RIGHT PACK. DUCT PRESSURE WAS CONSTANT & ADIQUITE WHOLE TIME. PREFORMED AIR CONDITIONING IBIT WITH FLOW SENSOR TEST, FOUND MESSAGE 21-55060 FLOW SENSOR OUT OF RANGE REMOVED NR 1 ENG FAMV IAW AMM 36-12-03-000-801. REQ INSP FOR KISS SEAL STEP G(1) OF AMM 36-12-03-400-801. COMPLIED CDCCL STEP G 1(A), (B) IAW AMM 36-12-03-400-801.ENG1 KISS SEAL GOOD.CLEAR TO CONTINUE. REF. GMM. 09-10-05 INSTALLED NR 1 ENG FAMV IAW AMM 36-12-03-400-801 UP TO STEP 3(I).   DUE TO ABOVE FAULT MESSAGE REPLACED FLOW CONTROOPERATED AS REQUIRED. GOOD TO CONTINUE. NO ISSUES NOTED.

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