What was found
UNABLE TO MAINTAIN CABIN PRESSURIZATION AT 240 WITH ONLY LEFT PACK IN OPERATION. NO WARNINGS OR LIGHTS ON CABIN PRESSURE CONTROLLER. CABIN ALTITUDE REACHED 11,000 FT AT FL 240. BITE CHECKED BOTH CONTROLLERS NR 1 HAD NO FAULTS, NR 2 FAULTED TEMPERATURE CONTROL VALVE. CHANGED RIGHT TEMPERATURE CONTROL VALVE, LEFT COMPRESSOR DISCHARGE OVERHEAT SWITCH, LEFT TURBINE INLET OVERHEAT SWITCH, LEFT PACK DISCHARGE TEMPERATURE SWITCH. RAN BOTH ENGINES, PRESSURIZED AIR CONDITIONER TO 5 PSI NO FAULTS. SYSTEM OPERATIONS CHECKED GOOD IAW AMM 21-62-00, 21-51-10, 21-51-41 AND 21-51-40, 21-51-42. AIRCRAFT OK FOR SERVICE. AIRCRAFT WAS GROUNDED.