What was found
AFT MAIN DECK SMOKE WARNING DURING DE-ICE WITH ENGINES OFF AND APU BLEED CLOSED. CHECKED CARGO AREA, SAW SOME SMOKE. FIRE RESCUE CAME ON BOARD AND CLEARED ACFT TO TAXI BACK TO THE RAMP. DURING TAXI, HAD AFT MAIN DECK LOOP B FAULT. RAN APU AND PACKS , FOUND NO FAULTS, OR WARNINGS. THERE IS A SLIGHT ODOR IN THE CARGO BAY WHILE PACKS ARE ON. REMOVED AND REPLACED THE NR 1 PACK COALESCER BAG IAW AMM 21-51-16-03. PERFORMED BOTH PACKS NR 1 AND 2 AIR CONDITIONING SYSTEM PURGE IAW AMM 21-51-00-03. NO ABNORMAL ODORS NOTED. PERFORMED A SATISFACTORY MAIN CARGO DECK SMOKE DETECTION SYSTEM CHECK IAW AMM 26-19-00-05. ALL MCD SMOKE DETECTORS OPERATE NORMALLY WITH NO FAULTS NOTED. OK FOR SERVICE.