What was found
LEFT PACK OFF LIGHT OCCURRED DURING T/O ROLL UNTIL 80 KNOTS AND DURING DESCENT BELOW 8000 FEET. REMOVED AND REPLACED LEFT PACK TEMP CONTROLLER AND BITE TEST OK PER AMM 21-51-14/401. LEFT PACK OPERATION NORMAL. REMOVED AND REPLACED LEFT PACK FLOW CONTROL AND SHUTOFF VALVE. OPS CHECK NORMAL WITH ENGINE HIGH POWER RUN (N1 95%) IAW AMM 21-51-00/401. CHECKED L-PTC BITE AND NO FAULTS FOUND. PRIMARY AND SECONDARY HEAT EXCHANGER CLEAN AND NO DAMAGE FOUND IAW FIM 21-51 FT 845, CHECKED WIRING, FLOW CONTROL VALVE, AND FLOW CONTROL CIRCUIT. NO DEFECTS FOUND. LEFT FLOW CONTROL VALVE WAS REMOVED AND REPLACED.