As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PACK TRIP OFF LIGHT ON TAXI OUT RESET AND CONTINUED TO OVERHEAT. GROUNDED - YES. PER B737-800 FIM 21-62 TASK 801 PERFORMED BITE OF PZTC 1 AND 2. NO FAULTS AND VERIFY PASSED. ATTEMPTED OPERATION OF LEFT PACK. PRESSURE SUPPLIED BUT ACM DID NOT TURN. REPLACED LT PACK ACM WITH NEW. OPS CK GOOD REF B737-800 AMM 21-51-04.