As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TEMP OUTPUT OF LEFT PACK INDICATES OFF SCALE -0 DEGREES CEL (RT PACK IS NOMINAL =20 DEGREE CEL) ALL ZONES COMFORTABLE AND CONTROLLABLE. GROUNDED - YES. CONFIRMED DEFECT. T/S PER B737-800 FIM 21-61 TASK 854. FOUND LEFT PACK TEMPERATURE BULB FAILED. REMOVED AND REPLACED LEFT PACK TEMPERATURE BULB PER B737-800 AMM REF 21-51-60-000-801/21-51-60-400-801. OP'S CKS LEAK CK'S GOOD.