Arrived on site to perform fall tune up on a 2017 Lennox system. Furnace and Evaporator coil located in attic. Client stated no issues just wanted filter checked out. Cycled heating mode and system operational. Found new ducting used and good condition. Filter is dirty which is causing airflow restriction in system. Recommend replacing filter to prevent air flow restrictions and reduce amount of dirt entering system. Blower assembly is good light dust. Wheel is good. Blower motor good. Amp drawls on both blower and inducer motor are both good and in range. Evaporator coil is good at this time. Heat exchanger is good. Drain lines are good and draining. Temperature rise is in range and heating. Recommend adding a whole house cleaning and purifying system to help keep system and home clean as well purifying air in home for a better air quality. No protection on high efficient systems. Recommend adding a surge protector on unit to protect it from getting damaged but electrical shortages