What was found
MDW - FLT 815 - AIR RETURN, NO EMERGENCY DECLARED LANDING UNEVENTFUL. AIRCRAFT ON DEPARTURE FROM MDW WOULD NOT PRESSURIZE IN AUTO, STANDBY, OR MANAUL. DEFERRED PER MEL 21-14-2, CI NR M912306. REF CI M912306. REPLACED LEAKING FLEX LINE AT 450 TEMP SENSOR PER MM 36-11-0 AND REPLACED BAD DOOR SEAL AT FORWARD CARGO DOOR PER MM 52-09-0. PRESSURIZED AIRCRAFT, LEAK CHECK AND OPS CHECK OK PER MM 21-00. (M)