Completed annual maintenance on a 2021 comfortmaker furnace. And during testing of the unit the technician found no electrical protection device, the air filter to be installed incorrectly, and ductwork to have large amounts of dust/hair build up. Customer not interested in electrical protection device at this time. Technician left fresh air corporation information for duct cleaning, as well as iwave information for air cleaner. Customer may call back at a later time for the install. Technician left filter beside unit as filter has recently been changed, and created inspection hole for combustion analysis. No issues at time of departure.