As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENG START, UPON RECALL CONT CAB ZONE TEMP LT ILL. GROUNDED - YES. ACCOMPLISHED B737-800 FIM 21-62 TASK 801, BITE TEST OF L PZTC FAULTING ZONE TRIM VALVE ON VERIFY TEST. ACCOMPLISHED FIM 21-62 TASK 835, VERIFY STILL FAULTING ZONE TRIM VALVE. REMOVED AND REPLACED LEFT PACK TRIM MODULATING VALVE REF B737-800 AMM 21-61-21. PERFORMED PACK TEMP CONTROL BITE REF FIM 21-62 TASK 801. NO FAULTS PRESENT. OPS TEST GOOD. ZONE TEMP LIGHT REMAINS EXTINGUISHED. ORIG SUBMISSION DATE: 11/1/2022