As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK LIGHT ILLUMINATED DURING TAXI, EXTINGUISHED UPON RESETTING AMBER CAUTION. GROUNDED - YES. REMOVED LH PACK TEMP CONTROL VALVE (TCV) PER B737-800 AMM 21-51-10-000-801. INSTALLED TCV PER AMM 21-51-10-400-801. PERFORMED TCV INSTALLATION TEST PER SAME, INSTALLATION TEST PASSED PACK ZONE TEMP. CONTROLLER BITE PASS NO FAULTS.