As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK LIGHT ILLUM IN FLT. RESET PER QRH, CAME BACK ON. REMAINED ON DURATION OF FLIGHT. RIGHT PACK NORMAL, PRESSURIZATION NORMAL, CONTINUE WITH LEFT PACK OFF. GROUNDED - YES. PERFORMED BITE TEST REF B737-900 FIM 21-62 TASK 801 FAULT TCV FOUND ON THIS PACK, FAULT CLEARED. NO FAULT ON STBY TCV. RAN PACK FOR 10 MINUTES AT VARIOUS TEMPERATURE AND PACK LIGHT DID NOT RETURN. PACK LIGHT RESET WITH NO ISSUES.