We have ac guy and plumber out and they have no clue. What's odd is we had a clog and they ran water with pulsating water attachment into an outside plug. When the water is running threw it, it smells like fresh water coming out of our ceiling vents. But within the day after the water has been turned off the sewer gas smell comes back.

We have had ac guy and plumber out twice and they have no clue. What's odd is we had a clog and they ran water with pulsating water attachment into an outside plug. When the water is running threw it, it smells like fresh water coming out of our ceiling vents. But within the day after the water has been turned off the sewer gas smell comes back. Coils have been cleaned, trap was not dirty.