What was found
FLT#626, FLL-RDU. (AIRCRAFT PERFORMED AN AIR TURN BACK TO FLL) 'AT 1500 FA IN AFT CALLED AND SAID AIR PRESSURE COMING OUT OF GASPERS WAS EXTREMELY STRONG. ABOUT THAT TIME AIIR PRESSURE IN FWD CABIN AND COCKPIT BECAME SO STRONG THAT WE COULDN'T HEAR EACH OTHER OR ATC . HOT AIR WAS MEL'D AND VENT AIR WAS -20C INTO COCKPIT. WITH PACK 1 OFF PRESSURE WAS REGULATED BUT TEMP WAS UNCONTROLLABLE WITH COCKPIT REACHING 88 DEGREES AT FULL COLD SETTING; FOLLOWING TSM 21-00-00-810-804-A, TRIM AIR VALVE (14HK) REMOVED AND REPLACED ON LP 3502694-1 (REMOVED AND REPLACED 14HK PRV AND LEAK CHECKED FOUND OK IAW AMM 21-63-63.), AND OPS CHECK ON LP 3502695-1 (PERFORMED OPS TEST FOR TRIM PRESS VALVE IAW AMM 21-63-00. TEST OK.). AS PRECAUTIONARY ZONE CONTROLLER (8HK) WAS REMOVED AND REPLACED ON LP 3502693-2 (REMOVED AND REPLACED ZONE CONTROLLER IAW 21-63-34. OPS CHK REQUIRED.) AND OPS CHECK ON 3502694-2 (PERFORMED OPS TEST FOR ZONE CONTROLLER IAW AMM 21-63-00. TEST OK.). FOUND BYPASS VALVE (30HH) FAULTING. REMOVED AND REPLACED VALVE IAW 21-61-53. TEST OK AND NO LEAKS.'