Completed furnace, maintenance and inspection. I cleaned flame sensor and wiped down furnace. I tested components and amp draws. I checked air pressure and temp splits. I tested for carbon monoxide, which read 0PPM. Air filter is almost 7 months old and is dirty. Customer has already ordered new filters so they will change it once they come in. The humidifier pad needed changed out. I did that today with customer approval. Talked with customer about air quality in the home. They are going to have floors and kitchen island redone in February so they would like to possibly look at having the ductwork cleaned while taking advantage of the UV special with the duct cleaning. They would most likely schedule it for late February or March. The furnace is operating within manufacture specifications at departure.