Upon arrival checked systems ductwork, made sure everything was connected, checked positions on mechanical and manual dampers, checked plenums, checked coil. Found that there was some cardboard in coil from packaging when unit was installed that wasn’t taken out causing cardboard to get wet and start to develop a little bit of growth on it. Took cardboard out. Return ducts have little to none dust on liners. Return plenum was pretty clean for age of system. Found no bacterial growth in plenums. Recommended adding a air scrubber uv light to help with indoor air quality, allergies and any air born bacteria or viruses. Emailed estimate.