What was found
IN CRUISE FLT, FLT ATTENDANTS REPEATEDLY SAY CABIN IS COLD. MOVED TEMP CONTROLLERS FULL WARM AND FWD DUCT TEMP STABLE AT ONLY 24 DEGREES C AND AFT 22 DEGREES C. NOTED L PACK TEMP PEGGED FULL COLD AND RT PACK 18 DEGREES C. ALTITUDE 34,000' AND DUCT PRESSURE APPEAR NORMAL AT L: 45 RT 42 PSI. OAT -48 DEGREES C FAIRLY WARM MOVING CONT CAB TEMP AFFECT CABIN TEMPS SIMILARLY EVEN THOUGH FULL WARM. GROUNDED - YES. PERFORMED PACK/ZONE TEMP CONTROLLER BITE TEST PER FIM 21-62 TASK 801. FOUND BAD LEFT TEMP CONTROL VALVE. REMOVED AND REPLACED LEFT TEMP. CONTROL VALVE PER AMM 21-51-10. OPS CHECK GOOD NO LEAK.