What was found
FLT 717 JFK-SJU, AT FL 370 WITH PACK 2 MEL OFF, BLEED 1 OVERHEAT RESULTING IN LOSS OF PRESSURIZATION. EMERGENCY DESCENT TO 10000 FEET BLEED 1 MAX TEMP 265, MAX CABIN ALTITUDE 12000FT SAFETY VALVE OPENED. REMOVED AND REPLACED THERMOSTAT FAN AIR VALVE CONTROL (7170HM1) IAW 36-11-43 ALL NORMAL.