You can feel the bad odor coming from the air vents of your house or office. In some cases, the smell is persistent. In other cases, it comes and goes and its intensity changes over time. Even though the symptoms may vary, they are a sign of a serious problem which must be identified and dealt with quickly. Find out more about the main causes of foul smell coming from the air ducts and how to resolve them. Less often, the bad odor can come from gasses which have been released into the air ducts. If the heat exchanger of the HVAC system ha... read full review »