What was found
AFTER ENGINE START RT ENG BLEED WILL NOT TURN ON AC RETURNED TO GATE AND MAINTENANCE GROUNDED AC. AND DEFERRED RH ENGINE BLEED FOR DEPARTURE IAW MEL ABX-36-11-1-2A-1. RETURNED AC TO SERVICE AND AC DEPARTED .RE ACT PRSOV AND FAN AIR VALVE SWAPPED LEFT AND RIGHT AIR SUPPLY CONTROL CARDS RAN ENG NO HELP REINSTALLED ORIG POSITION MANUALLY CYCLED PRSOV SMOOTH PERFORMED HPSOV THUMB TEST PER AMM 36-00-21 TEST GOOD HPSOV RETURNED TO NORMAL C/W MPM 36-11-1-2A-1 AND 36-12-2 .THEN REMOVED AND REPLACED R ENG PRSOV PER AMM 36-11-09, C/W RE-ACTIVATION PROCEDURES PER MEL MPM 36-11-1-2A-1 & 36-12-2 OP'S CHECK OK, DUCT PRESSURE NORMAL. THIS ACTION CLEARS DI 50024, A/C REMAINS NO ETOPS, PLACARD REMOVED.