Arrived on site to preform a 20 point maintenance inspection on a 3 year old furnace. Upflow in garage turned unit on, and verified the proper heating sequence of operation. Next took an inducer motor amp draw, inducer was wishing design range. Checked flue vent and and gas piping for any leaks or smells. Took a temp rise, temp was within range of data plate. Opened unit and inspected blower motor, blower should some slight signs of dust buildup, filter was dirty and was changed 16X24X1 Merv 11 filter. Checked condensate drain condensate was clear and draining at the time of maintenance. Static pressure was a little high dude to lack of supply airflow. Homeowner is aware. Recommended surge protection for indoor unit for, rolling brownouts and surges. Customer did not wish to renew membership at this time. Unit was operating upon departure.