# SDR CALA2026101320320

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: October 8, 2026
- Submitted: October 13, 2026
- Operation: Air carrier
- Aircraft: [N16732](https://openairdocs.org/aircraft/N16732), registered now
- Make and model: Boeing 737724
- Aircraft serial: 28948
- Aircraft time: 82,248 hours, 30,848 cycles
- System (JASC): [2140 · Heating System](https://openairdocs.org/jasc/2140)
- Part: Controller
- Part number: 39811611
- Part serial: P134
- Condition: Faulty
- Location: Zone 100
- Part time: 10,444 hours, 5,013 cycles
- Stage of operation: CL
- How discovered: O
- Nature of condition: O
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/CALA2026101320320

## Discrepancy

UNCONTROLLABLE FLT DECK TEMP. ONLY HOT. ONLY COOLED W/LT PACK OF F. DEBRIEF FROM CA, FLIGHT DECK TEMPERATURE HOT WITH LT & RT PACKS ON, LT AIR MIX VALVE GAUGE READING RIGHT ABOVE HALF ON HOT SIDE, PERFORMED AUTO & MANUAL CONTROL INPUTS WITH NO CHANGE IN TEMP, PLACED LT PACK SWITCH TO OFF, FLIGHT DECK TEMP COOLED OFF,  MOVE TEAM HOOKED UP TO AIRCAFT, NOT ABLE TO BITE TEST. DEBRIEF FROM CA, FLIGHT DECK TEMP HOT WITH LT & RT PACKS ON, LEFT AIR MIX VALVE GAUGE READING RIGHT ABOVE HALF ON THE HOT SIDE, PERFORMED AUTO & MANUAL CONTROL INPUTS WITH NO CHANGE IN TEMP, PLACED LT PACK SWITCH TO OFF, FLIGHT DECK TEMPERTURE COOLED OFF,  MOVE TEAM HOOKED UP TO AIRCAFT, NOT ABLE TO BITE TEST. LOCKED BY TOMC FOLLOWED FIM 21-61 TASK 844. R & R AIR MIX VALVE IAW AMM 21-61-02-400-801. OPS CHK GOOD. NO FAULTS NOTED AT THIS TIME.

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