What was found
DURING CRUISE FLIGHT, LEFT ENGINE BLEED OFF LIGHT ILLUMINATED. UNABLE TO MAINTAIN CABIN PRESSURIZATION. - TROUBLESHOT LEFT ENGINE BLEED AIR SUPPLY SYSTEM IN ACCORDANCE WITH FAULT ISOLATION MANUAL 36-10 FAULT TREE 813. LEFT ENGINE BLEED AIR SYSTEM CHECKED NORMAL. WHILE PERFORMING TEST OF CABIN PRESSURIZATION SUPPLY SYSTEM, FOUND THE RIGHT AIR CONDITIONING SYSTEM AIR CYCLE MACHINE DEFECTIVE. REPLACED THE AIR CYCLE MACHINE PER AIRCRAFT MAINTENANCE MANUAL 21-51-03. PERFORMED CABIN PRESSURIZATION SYSTEM TEST PER AIRCRAFT MAINTENANCE MANUAL 21-31-00. SYSTEM TESTED NORMAL. PERFORMED CABIN PRESSURIZATION CONTROL SYSTEM TEST PER AIRCRAFT MAINTENANCE MANUAL 21-31-02. SYSTEM TESTED NORMAL.