What was found
CABIN AIR CPRSR L2 CABIN AIR COMPRESSOR L2 HAS FAILED OR HAS A FAULT, IS UNAVAILABLE, OR HAS BEEN SELECTED OFF. AFTER ENG START FLT DECK VERY HOT W/ACRID ODOR NO EXISTING FAULT AND FAULT HISTORY . GROUND TEST CABIN AIR CONDITIONING TEMP CONTROL SYS , SYS TEST LT & RT PACK SYS AIR ON PASSED . INSPECTED PACK LT & RT NO FAULT NOTED . RAM AIR & VENT FAN INSPECTED NO FAULT NOTED. RECIRC FAN CHECK, NO FAULT . CARRIED OUT SMOKE & FUMES NO ACRID ODOR NOTED IAW FIM DMC-A-21-20-F5-72A-421A-A. DEFECT DEFERRED IAW MEL 2151CE. L2 CAC DEACTIVATED IAW DDG 21-51-01-02-01-01. MAINT REQUIREMENTS COMPLIED WITH. INOP PLACARD APPLIED. L2 CAC REACTIVATED PER DDG21-51-01-02-01-01. NIL MSG EXIST. L PACK CONTROL SYS TEST IAW AMM DMC-B787-A-21-51-00-00A-300B-A, CMCF GROUND TEST: 21- CABIN AIR CONDITIONING/TEMP CONTROL SYS, SYS, LT PACK SYS AIR ON/OFF CARRIED OUT. TEST PASSED NO FAULTS.