B727 CREW OPERATES AN AIR-CONDITIONING PACK THAT IS DEFERRED INOP EVEN THOUGH IT IS A FAILURE OF THE COOLING DOORS THAT IS THE PROB.

Narrative

CREW OPERATED L AIR CONDITIONING PACK WHEN THE PACK HAD BEEN PLACED ON MEL (NOT SUPPOSED TO BE OPERATED). THE MEL PLACARD STATED 'L PACK COOLING EXIT DOORS FAILED FULL CLOSED' AND REFERRED TO MANUAL WHICH JUST SAYS 'AIR CONDITIONING PACKS.' WE DID NOT INTERPRET THIS CORRECTLY BECAUSE THE WORDS PACKS INOP WERE NOT WRITTEN IN THE MEL OR THE LOGBOOK. AFTER LNDG AND DISCUSSING THE PROB WITH MAINT IT WAS CLR THE PACK WAS NOT SUPPOSED TO BE USED. THE ENGINEER DID A GOOD JOB OF MONITORING THE PACK TEMP AND THERE WAS NO DAMAGE DONE BY OPERATING THE PACK. THE PROB WE HAD WAS HOT OUTPUT AIR IN THE CABIN IN ORDER TO KEEP THE PACK FROM OVERHEATING. WE ELECTED TO TURN THE L PACK OFF DURING THE CLBOUT AND THAT COOLED THE CABIN OFF. WE ALSO COMPLIED WITH SINGLE PACK ALT RESTRS. THE MAIN PROB HERE WAS THAT NOTHING JUMPED OUT AT US AND SAID 'DO NOT USE THE PACK.' SUPPLEMENTAL INFO FROM ACN 490919: A 'DIFFERENT' MEL WOULD HAVE ALLOWED US TO OPERATE THE PACK WITH CERTAIN RESTRS BUT THE MEL NUMBER THAT MAINT USED CALLED FOR THE PACK TO BE INOP/UNUSABLE. IN THE RUSH; CREW FAILED TO NOTICE THE DISCREPANCY BTWN THE WRITE-UP AND THE MEL THAT MAINT USED.