What was found
UPON CLIMB OUT AT 1500' FLIGHT ATTENDANT ADVISED OF CABIN IN FUMES & SMOKE, WHITE. SMOKE TAPERED OFF SLIGHTLY UPON LEVEL OFF & RETURNED DURING DESCENT. PERFORMED TROUBLESHOOTING IAW FIM TASK 21-20-00-810-801-A, UP TO TASK OR STEP NR 7. FOUND RECIRCULATION MUFFLER OFF FROM JOINING DUCT, SECURED IAW AMM 21-24-02, RAN ACFT IAW 21-10-00 & AMM72-00-00, OPERATIONS CHECKED GOOD, NO FAULTS NOTED.