What was found
ON T/O, VAPOR WAS PRESENT IN CABIN AND AFT SMOKE DETECTOR ACTIVATED AS PRECAUTION. RETURN TO FORT LAUDERDALE. REMOVED AND REPLACED BOTH COALESCER BAGS, ADJUSTED SENSE LINE (APU) WIPE DUST, CLEAN OFF RESIDUE. RAN BOTH ENGINES AT HIGH POWER AND NO SMOKE NOTED. ALL WORK IAW 21-00.