As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PREFLIGHT LEFT PACK LIGHT WAS ILLUMINATED. GROUNDED - YES. ACCOMPLISHED #1 TEMP CONTROLLER BITE TEST SHOWS THIS PACK TCV UNABLE TO RESET FAULT. SWAPPED TEMP CONTROLLER AND FAULT STAYED WITH #1 POSITION. SWAPPED CONTROLLER BACK TO ORIGINAL POSITIONS REF B737-900 AMM 21-61-20. BITE TEST STILL SHOWS THIS PACK TCV AND PACK LIGHT WILL NOT RESET. REF B737-900 FIM 21-62 TASK 801. REMOVED AND REPLACED TEMP CONTROL VALVE IAW AMM 21-51-10-400-801. OPS TEST GOOD, LEAK CHK GOOD. GROUND VERIFICATION SUCCESSFUL.