What was found
FLIGHT 1772, CLT-DFW - AFTER TAKEOFF THE AIRCRAFT WAS UNABLE TO PRESSURIZE. THE CREW WAS PERFORMING OPS PROC WITH ECS OFF THE APU BLEED CLOSED PROPERLY AT 500FT, LEFT BLEED OPENED MOMENTARILY BUT THEN CLOSED RESULTING IN THE FOLLOWING EICAS MESSAGES; "X BLEED FAIL", "BLEED 1 OFF", "PACK 2 OFF", AND "BLEED APU VALVE". THE FLIGHT REMAINED BELOW 15,000 FEET WITH THE APU POWERING PACK 1. MAINTENANCE THE NR 2 PACK CONTROL VALVE.