As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER START WE ESTABLISHED OUR BLEED CONFIGURATION AND WE HAD A PACK LIGHT ILLUMINATED. INITIALLY THE PACK LIGHT EXTINGUISHED WITH THE MASTER CAUTION PUSHED BUT SEVERAL SECONDS LATER THE PACK LIGHT RETURNED ON. GROUNDED - YES. REMOVED AND REPLACED PACK/ZONE TEMP CONTROL VALVE LH OPS CHECK GOOD REF B737-800 AMM 21-51-10