What was found
DURING FLIGHT, THE LEFT AC PACK LIGHT ILLUMINATED, CHECKED LIST WAS RUN AND LIGHT EXTINGUISHED WITH MASTER CAUTION RESET. ACFT GROUNDED. VERIFIED FAULT, ACCOMPLISHED A PACK/ZONE TEMP CONTROL BITE NR 2. NO FAULTS, NR 1 FAULTS THIS PACK TCV (V139). REMOVED AND REPLACED THE TEMP CONTROL VALVE V139 IAW 21-51-10-000-801, AND 21-51-10-400-801. RESTORED AIRCRAFT TO ORIGINAL CONFIGURATION BY CONNECTING THE CONNECTORS TO TCV. PERFORMED TEMP CONTROLLER BITE TEST IAW AMM 21-61-00-700-806-002. RAN APU WITH BLEED AIR NR 1 PACK, NO LEAKS DETECTED.