As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RIGHT PACK LIGHT ILLUMINATED AT GATE WITH BOTH PACKS ON. GROUNDED-YES. RAN BITE CHECK AND FOUND PACK TCV FAULTED. REMOVED AND REPLACED TEMP CONTROL VALVE, REF B737-900 AMM 21-21-10. OPS CHECK GOOD. CONTINUED RUNNING PACK AND FOUND THE AIR CYCLE MACHINE TO BE "CLUNKING". REMOVED ACM, PER AMM 21-51-04 AND FOUND TURBINE BLADES TO BE HITTING ACM CASE. INSTALLED ACM, PER AMM 21-51-04. OPS CHECK GOOD, NO LEAKS NOTED. PACK LIGHTS REMAINS EXTINGUISHED.