What was found
STATUS MSGL ENGIINE EEC C1 MAINT TEXT: CREW REPORT PROBLEM ON LEFT ENGINE. BITE CHECK OF PIMU SHOWED EEC CHANNEL A AOC FD-BK FAIL AND EEC CAT 1 CH A AND B. REF PIMU MSG INDEX PAGE 600, MSG NUMBER 351-28 FOR TROUBLESHOOTING INFO DEACTIVATED VALVE IN OPEN POSITION PER MEL CARD 75040. PLUG DISCONNECTED AND SAFTIED AND PLACARD PLACED ON LOWER EICAS. REPLACE NR 1 AIR OIL HEAT EXCHANGER AND VALVE ASSY. REPLACED PER AMM 79-21-09 THROUGH 3 (E), CONTINUE WITH 3(F) PUT AIRPLANE BACK TO ITS USUAL CONDITION. ACCOMPLISHED 3F THROUGH THE END CHECKS OKAY.