Are you constantly using lighting candles or using scented plug-ins in order to make your interior smell better? Does it seem like your odor issues are even more pronounced when your HVAC is turned on? Many people have serious problems with their home odors because they don't properly clean the HVAC system. There are several points at which odors can take hold in your HVAC system. This article explains how homeowners can find the source of bad smells in the HVAC system.
Heat or AC?
If you have increased odors coming out of your air registers when both your heat and air conditioner are running, the obvious culprit is the duct system. But, if you notice that the odors are only coming out when your heat is on, or only coming out when your AC is on, then you know that the odor isn't originating from the duct system. That being said, cleaning your ducts will probably be necessary once you find and eliminate the source of the smell. So, if you have smelly heat, you need to have your furnace checked. If you have smelly AC, you want to have your air conditioning unit checked.
If your air is smelly when both your heat and AC are running, this doesn't necessarily mean that your odor is only coming from the ducts. Many split air systems have air handlers that circulate the air from the furnace and the air conditioner into the duct system. So, when the air passes through the air handler, it can pick up the odors and circulate it into your ducts. The odds are, replacing your filters isn't going to have a huge effect on overall odors. Most odors are caused by mold buildup. A HEPA filter that regularly replaced can definitely decrease the likelihood of of the formation of odors caused by mold, but they aren't going to clean or remove mold that already exists within your system.
Ultimately, it might be possible to find what is causing your HVAC system to be smelly, but it'll probably be much more difficult actually take care of it. Remediate mold and odor causing bacteria is something that professionals can do much more efficiently than homeowners who probably don;t have the right tools or knowledge of the job. In the end, it usually makes more practical sense to have a professional, such as from Advanced Air Quality Services, eradicate the odors and you can rest assured that everything is removed.