Performed preventative maintenance for a Lennox furnace model #Sl280uh110v60c-05, serial #5917d13646. I powered the system down and removed the access panels. Removed and cleaned carbon off of the flame sensor and cleaned out the burners and burner box. Checked the pressure switch for clogs and checked all electrical connections to ensure that they are secure and in good condition. The blower motor and blower wheel are clean and in good condition. The air filter was recently replaced by the homeowner 20x25x1. I performed humidifier service for a healthy climate powered humidifier. I removed the old #35 water panel and cleaned out the housing and drain. I installed a new #35 water panel supplied by the homeowner. I powered the system back up and called for heat. Took a combustion analysis test and received the following readings, o2 is 10.5% and the co levels are 17ppm . I tested the humidifier for proper operation and leaks. The inducer motor amp draw is .26 and the blower motor amp