Arrived on site to perform fall tune up on a 2013 Lennox system. Furnace and evaporator coil located in attic. Client stated no issues and was good cycled heating mode on and good. Filter was due for replacement but client stated it’s okay and will leave it in. Recommend replacing to reduce dirt entering system and airflow restriction to creat stress wear on motor. Found new flex ducting used and good condition. Blower assembly good dust accumulating. Motor is good and amp drawls are in range. inducer motor is good and amp draws are in range. Coil is good. Heat exchanger is good. All safety switches are operational. Drain lines good slight debris accumulating Indicating dust and debris is entering system over time. Temperature rise is good and in range. Voltage of furnace at 122. No protection on high efficient system. Recommend adding surge protectors to prevent system from getting damaged from electrical surges and power outages that can damage or short out components or even s