What was found
AFTER TAKEOFF, ACRID FUMES APPARENT, THE SOURCE COULD NOT BE IDENTIFIED. FLIGHT ATTENDANTS REPORTED IT WAS NOTICIABLE THROUGHT THE CABIN. STRONG FUMES NOTICIABLE IN THE COCKPIT. PERFORMED CONDITIONAL INSPECTION IAW AMM 05-51-56. PERFORMED FIM 21-31, TASK 806. REPLACED THE HEPA FILTER IAW AMM 21-25-01. REPLACED LEFT PACK WATER SEPARATOR BAG IAW AMM 21-50-05. THE SOURCE OF THE FUMES WAS DETERMINED TO BE THE LEFT ACM .