As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT CRUISE LEFT "PACK" LIGHT ILLUMINATES ON RECALL AND EXTINGUISHES ON MASTER CAUTION RESET. QRH COMPLIED WITH, NO NOTICEABLE CHANGE IN CABIN PRESSURE, ENGINE AND WING ANTI-ICE WERE OFF. GROUNDED-YES. REMOVED AND REPLACED LT FLOW CONTROL VALVE, REF B737-800 AMM 21-51-01. OPERATIONS CHECK NORMAL, REF AMM 21-61-00 PACK/ZONE TEMP CONTROL BITE TEST PASSED. GROUND VERIFICATION NORMAL.