What was found
FLT 0751 - DURING CLIMB AT 6000 FT A NR 2 ENGINE BLEED OCCURRED (315 DEG C NOTED) , THE CROSS-BLEED VALVE OPENED AND BOTH PACKS WERE RUNNING OFF THE NR 1 ENGINE, ATTEMPTED TO START APU BUT THE APU AUTO SHUTDOWN, NR 1 ENGINE THEN EXPERIENCED A BLEED FAULT, AIRCRAFT TURNED BACK TO PHX. MAINTENANCE TROUBLESHOT AND REPLACED THE NR 1 & NR 2 ENGINE FAN AIR VALVES IAW AMM 36-11-54-401, PG. 1-6, OPERATIONAL CHECKS WERE GOOD IAW AMM 71-00-00-710-043. AS A PRECAUTION BOTH THE NR 1 & 2 ENGINE TEMPERATURE CONTROL THERMOSTATS WERE REPLACED. MAINT ALSO R&R THE APU PNEUMATIC SENSOR ASSEMBLY TO CORRECT THE APU AUTO SHUTDOWN PROBLEM, LEAK AND OPERATIONAL CHECK WERE GOOD.