When I turn my ac unit on it smell like sum1 has used da bathroom I have had a plumber 2 check my pipes and clean my spectic tank and da smell is still der what can I do know

When your A/C is on it mixes all smells and tempratures to one area--- the return air grill and then it circulates it through out the house through the supply registers(the smell could come from anywhere). One thing to check is to make sure your condensation line on you blower section is not tied in with your plumbing.