What was found
LEFT PACK TRIP LIGHT CAME ON WHEN TRYING TO USE APU FOR A/C ON THE GROUND. IT WOULD NOT RESET WITH MASTER CAUTION. GROUNDED - YES. CONFIRMED FAULT. ACCOMPLISHED PACK/ZONE TEMP CONTROLLER BITE TEST BOTH LEFT & RIGHT SIDE REF B737-800 AMM 21-61-00-700-806-002, NO FAULTS. DISCONNECTED (D532) FROM COMPRESSOR DISCHARGE OVERHEAT SWITCH REF B737-800 FIM 21-53 TASK 801 "LEFT PACK LIGHT ILLUMINATED & WILL NOT RESET" FAULT ISOLATION, LEFT PACK TRIP LIGHT STAYS OFF. REMOVED L/H ACM REF AMM 21-51-04, FOUND TURBINE BLADES BROKEN & A PIECE DISLODGED TO THE SIDE OF THE INTERIOR WALL & ACM FROZEN. INSTALLED NEW LEFT ACM IAW AMM 21-51-04. ABLE TO CONTROL LT PACK TO 20C DEGREE.