The Returns air are the big vents with the Air Filters. Their job is to bring air to the AC unit, that’s why we put an Air Filter here to reduce the amount of dust that gets into our system. It’s recommended to replace the Air filters every 3 months as part of the routine maintenance.
In most cases, that’s the place where the mold start to grow. Hot air flows from the Return air through the AC system to the Evaporator Coil (which is cold) the confluence between hot air and cold creates condensation and moisture, those leads to mold growth eventually. This process can be particularly accelerated in Southern areas where the temperature is high most of the year.
The air from the Plenum Box flows through the air ducts to the house. As you understand, the bacteria and germs flow directly through the air ducts and sink there. Throughout the process that’s the longest part. We use TruckMaster II connected to a HEPA filter Vacuum cleaner (shown in video) that brush and vacuum the duct at the same time. We also use sanitation to remove mold spores and bacteria from the air ducts.
sometimes, we can notice mold spots on the grilles, to remove them, we take off each one of the grilles and cleaning them with a pressure washer mixed
with sanitizer to eliminate any mold spore. in some cases we recommend to replace them.
Eventually, after we removed the mold from the system, we highly recommend to install a UV light to prevent mold growth again. As we all know, mold fungus grows only in dark and cool places, UV lights are simulating the sun light and preventing the possibility for the mold to grow.