What was found
LEFT PACK TEMP EICAS MESSAGE @ 4000 FEET. DEFERRED PER MEL 21-51-01-01, MDDR 141737, CAT C, DUE 10FEB21. MAINTENANCE ACTIONS C/W. PACK FLOW CONTROL SHUTOFF VALVE CLOSED. DP @ 18:43.1209080 - M1: OPS CHECKED PACK IAW 21-51-00, FLOW CONTROL VALVE OPERATED NORMAL. NO FAULTS ON LT PACK BITE IAW FIM 21-51 FT844, SUSPECTED INTERMITTENT PACK CONTROL CARD. R & R LEFT PC CARD IAW WDM 21-51-11. OPS TEST NORMAL. 1209081 - M4: FLIGHT DECK TEMP REMAINED @29C THROUGHOUT FLIGHT. DUE TO ITEM NR1 LP 1209080 SUSPECT MECHANICAL FAILURE OF FLOW CONTROL AND SHUT OFF VALVE. R & R IAW AMM 21-51-01 OFF PART: PN 396496-1, SN 7070. REF LP 1209082 ITEM 8 FOR OPS CHECK. LP 1209082 - M8: PERFORMED ENG RUN IAW AMM 71-00-00, OPS CHECK OF LT PACK NORMAL AT THIS TIME. THIS CLEARS DMI 141737. ALL PLACARDS REMOVED.