Demand call for system having some kind of biological growth on the supply side and some of the ductwork not being properly sealed. Upon arrival the customer took me to the attic to show me the areas of concern. Some of the ducts attached to the supply boxes and mixing boxes had minor air leaks causing some growth around the connections. I was able to remove the growth and reseal the ductwork, I informed the customer that I can’t guarantee the growth won’t come back but properly sealing the ductwork and adding a return and supply vent in the attic to help with the humidity of the foamed attic will definitely help prevent it from coming back. Customer does have an air scrubber and has replaced the bulb in it already and he will like to add the vents in the attic to maximize the defense against the growth. Customer signed the estimate and paid a $100 deposit that will go towards the total due when the work is completed. I informed him that the office will call him tomorrow morning to