AN AIRBUS A320 WAS DISPATCHED IN NON COMPLIANCE WITH THE L PACK DEFERRED BUT NOT LOCKED OUT PER THE MEL SPECIAL PROCS.

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ACFT ARRIVED AT THE GATE. THE CAPT REQUESTED MAINT AND I WENT UP TO TALK TO HIM. HE RPTED THAT ZZZ MAINT HAD MEL'ED THE L PACK DUE TO A PACK FAULT; BUT HE HAD OPS TESTED IT ON THE WAY FROM ZZZ TO XYZ AND BOTH PACKS CHKED OUT GOOD. I CHKED THE LOGBOOK AND ZZZ MAINT HAD MEL'ED THE #1 PACK AND SIGNED OFF THE SPECIAL PROC AS HAVING BEEN ACCOMPLISHED. SPECIAL MAINT PROC CALLS FOR THE PACK VALVE TO BE LOCKED OUT. I CALLED MAINT CTL AND THEY TOLD ME THAT IF THE PACKS OPERATED NORMALLY THEN THE PACK VALVE COULD NOT HAVE BEEN LOCKED OUT. THE PANEL THAT HAS TO BE REMOVED TO GET TO THE PACK VALVE HAS 49 SCREWS HOLDING IT IN AND TAKES 20 MINS TO REMOVE AND REPLACE IT. DUE TO TIME CONSTRAINTS ON THE FLT; I TOOK THE CAPT'S WORD THAT THE PACK WORKED AND MAINT CTL'S ASSURANCE THAT THE PACK VALVE COULD NOT HAVE BEEN LOCKED OUT AND I REMOVED THE MEL ON THE PACK WITHOUT PULLING THE PANEL TO VERIFY THAT THE PACK VALVE WAS NOT LOCKED OUT. AFTER THE PLANE DEPARTED; I BEGAN TO THINK THAT FIRST; THE CAPT SHOULD NOT HAVE BEEN OPERATING AN MEL'ED PACK AND IF I DID NOT HAVE THE TIME TO CHK TO SEE THAT THE PACK VALVE WAS NOT LOCKED OUT; I SHOULD HAVE LEFT THE PACK ON MEL. THE REASON THAT THE CAPT AND MAINT CTL WANTED IT TO BE REMOVED WAS DUE TO ALT RESTRS GOING ACROSS WATER.