What was found
LAX - FLT 04 - AIRCRAFT WOULD NOT PRESSURIZE IN AUTO MODE SHORTLY AFTER TAKEOFF FROM LAX. F/A SAID R-4 DOOR AND L-4 DOOR NOT PLUGGING PROPERLY AFTER TAKEOFF. MANUAL MODE WORKED BETTER AFTER REDUCTION OF POWER AND HIGH STAGE BLEED CAME ON. AIRCRAFT RETURNED TO GATE AFTER 20 MINUTES IN THE AIR. (ATB) REPLACED AUTO PRESSURE CONTROL. BITE CHECKED SYSTEM OK. INSPECTED ALL CABIN AND CARGO DOOR SEALS. OK. PRESSURIZED AIRCRAFT AND OPS CHECK NORMAL. (X)