Customer called due to heat not working properly and to have preventative maintenance on the furnace if it could be fixed on site. Upon inspection I found the safety switch for the blower motor was not plugged in after we replaced the blower motor over the summer. Tested system after and it fired up without issue. Inspected all the electrical components. Replaced the customer supplied air filter 16x25x1. Confirmed proper high and low voltages cleaned the burners, flame sensor and burner compartment. Performed a combustion analysis on the furnace. System is operating at 82% efficiency with a CO level of 23ppm. System is operating properly at this time. Model #SL280UH090V36B-03 Serial #5913J26446