PILOT OF A B747-400 REPORTS OF UNCONTROLLABLE HIGH CABIN AND COCKPIT TEMPS OVER 90 DEGREES FOR APPROX THREE HOURS IN FLIGHT. SAME ACFT; SAME CONDITION FOR TWO MONTHS; NUMEROUS WRITE-UPS; SIGNED-OFF BY MAINT.

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THIS ACFT HAS BEEN IN SVC WITH A PACK 2 PROB SINCE EARLY JUNE ACCORDING TO MAINT HISTORY. ON OUR FLT; THE CABIN TEMP ON THE GND IN ZZZZ WAS OVER 90 DEGS F AND THE COCKPIT WAS 99 DEGS F. THE ACFT COULD NOT BE COOLED TO NORMAL TEMP FOR ABOUT 3 HRS INFLT; NOT INCLUDING GND TIME. THESE TEMPS PRESENT A DANGER OF HYPERTHERMIA TO ELDERLY PAX AND THOSE WITH OTHER HEALTH CONCERNS; OF WHICH WE HAD MANY ON BOARD. MANY PAX WERE COMPLAINING ABOUT THE INTOLERABLE CONDITIONS. THE ITEM KEEPS GETTING CLRED WITH NO REPAIR. I AM ESPECIALLY CONCERNED ABOUT MAINT HISTORY ITEMS WHICH CLRLY INDICATE THAT COCKPIT AND CABIN TEMPS OVER 90 DEGS F FOR 3 HRS INFLT; NOT INCLUDING GND TIME OF 30 MINS; IS AN ACCEPTABLE CONDITION. THESE CONDITIONS PRESENT A HAZARD TO CREW MEMBERS AND PAX ALIKE; AND SHOULD NOT BE ALLOWED TO CONTINUE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED HE HAS FLOWN THE B777'S AND B747-400 FOR A LONG TIME. BUT HIS CARRIER'S -400'S ACFT SEEM TO SUFFER NUMEROUS AIR CONDITIONING PROBLEMS IN COMPARISON TO THE B777; WHICH HE BELIEVES WAS FAR MORE RELIABLE WITH FEWER AIR CONDITIONING ISSUES. REPORTER STATED HE RECENTLY BECAME AWARE THE -400 WITH THE CONTINUING TEMP AND PACK PROBLEM WAS APPARENTLY REPAIRED AFTER MAINT REPLACED A FAILED PACK FLOW CONTROL VALVE. HE IS NOT AWARE OF ANY FURTHER PROBLEMS WITH THE CABIN TEMP SINCE.