What was found
PHX - AIR TURNBACK - FLT 0256 - WHILE CLIMBING OUT OF PHX EN ROUTE FOR PHL RECEIVED ECAM CAUTION AIR ENGINE NR 1 BLEED FAULT, BLEED TEMPERATURE EXCEEDED 300 DEGREES, TURNED BACK TO PHX DUE TO POSSIBLE ICING CONDITIONS. MAINTENANCE REMOVED AND REPLACED THE NR 1 ENGINE TEMPERATURE CONTROL THERMOSTAT IAW AMM 36-11-43-401. PERFORMED ENGINE RUN, OPERATIONAL CHECK WAS GOOD. VENDOR CONFIRMED FAILURE OF UNIT CITING THE FILTER WAS CONTAMINATED WITH POLLUTION. RESTORED UNIT BY CLEANING THE PRESSURE REDUCING CLAPPER / GUIDE AND FILTER, AND REPLACING SCREW LOCKS AND PACKING.