OK....i thought you said the smell was coming from the AC outlet vents. Did you see water laying in the cooling coil pan when you cleaned it? The larger condensing coil can be seen from the roof but thats not the problem. . Remember the cooling coil is internal can not be seen with out some disassembly of the unit. (1-1.5 hour job). I have been working HVAC for 15 years and 99% of the time the smells come from a blocked condensate drain, or the unit being install out of level causing the drain to run uphill.