What was found
FLIGHT 5134 - SFO/MRY - PILOT REPORTED, THAT WHILE INFLIGHT A LARGE AMOUNT OF SMOKE DEVELOPED IN THE FLIGHT DECK AND CABIN AREA. THE LEFT FLOW CONTROL WAS TURNED OFF AT WHICH TIME THE SMOKE CEASED. THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE PERSONNEL PERFORMED LENGTHY RT AND LT ENGINE GROUND RUNS WITH LT AND RT ACMS OPERATING IN BOTH MANUAL AND AUTO MODES. OPERATIONAL CHECKS WERE NORMAL WITH NO SMOKE DETECTED, RESIDUAL OR OTHERWISE. AIRCRAFT RETURNED TO SERVICE.