Arrived to evaluate a system a homeowner would like to replace. Homeowner mentioned that the system is still working but is making a good bit of noise. Found that the system is 30 years old. Opened up the system and found that the interior of the equipment is heavily coated in bacterial growth. Performed a static pressure test and found that the system is flowing air very well. Considering the amount of bacterial growth and dust in the system, would recommend replacement considering the high cost of cleanings.