What was found
AFTER SELECTING ANTI-ICE ALL ON, AVIONICS FAN OVERRIDE, BLEED AIR 3 OFF, BLEED AIR 1 OFF, PACK 2 FAULT. CABIN PRESSURE STARTED TO CLIMB, ELECTED TO DESCEND TO FL280. AFTER SWITCHING AIR CONTROL CHANNEL, SAME FAULTS RESUMED. SELECTING ALL ANTI-ICE OFF, ALL FAULTS EXTINGUISHED. NO CURRENT FAULT AND LAST FLIGHT FAULT ON THE PSC 1 ,PSC 2 AND ESC.PERORMED ALL THREE ENG IDLE RUN AS PER AMM 71-00-00-2-2 , PERFORMED FUNCTIONAL TEST OF THE ENGINE NOSE COWL ANTI-ICE SYSTEM PER AMM 30-11-00-5 AND WING ANTI-ICE - ADJUSTMENT/TEST PER AMM WING ANTI-ICE ADJUSTMENT/TEST PER AMM 30-22-00-5-1,ALL TEST SATIS AND THE PARAMETERS NORMAL.NO HISTORY WITHIN 90 DAYS,ITEM CLOSED.A/C OK FOR SVC.