Performed furnace maintenance on a 2015 Lennox gas furnace. Customer reports good working condition prior to visit. System is heating high but in range. Filter is very dirty. Sensors cleaned and tested. Primary blower and combustion blower are reading in range. Gas valve and ignitor were tested and recorded. Condensate lines are clear, pump is operational. Furnace compartment and closet were vacuumed out. The furnace power source is connected only to a light switch which provides no protection. Recommending hard wired equipment protection that will protect the furnace as well has the smart hub and thermostat. Filter was replaced today. Homeowner is aware of the condition of the unit. System is operational.