What was found
STRONG ELECTRICAL BURNING SMELL WHILE TAXIING WITH BOTH ENGINES RUNNING. TROUBLESHOT PER FIM 21-21-00-810-806. IDLE RAN ENGINES IAW AMM 72-00-00. OPS CHECKED AIR CONDITIONING SYSTEM IAW AMM 21-51-00. COULD NOT DUPLICATE FAULT, NO SMELL NOTED. LT PACK PREVIOUSLY ON MEL, NO FURTHER DEFECTS NOTED. REMOVED AND REPLACED LT AIR CYCLE MACHINE IAW AMM 21-51 -08. OPS CHECK GOOD. VALVE TEMPERATURE CONTOL P/N GG670-95010-3 S/N 00241.