Completed furnace, maintenance and inspection. I checked components and amp draws. I tested air pressure and temp splits. I changed out air filter with customer provided filter. I wiped down furnace and cleaned flame sensor. I tested for carbon monoxide which red at zero PPM. Furnace is operating within manufacturer specifications. I talked with customer and showed them the blower wheel and how it is starting to build up some dust. I recommended that we check it again during the AC maintenance and possibly clean it at that time. We also talked about whole home surge protection as well as individual surge protection for the furnace in AC. Customer would like to wait on that and talk with spouse for now.