Performed preventative maintenance on a high efficiency Lennox system. Model #SLP98UH090XV60C, serial #5912C11786. I powered the system down and removed the access panels. Removed and cleaned carbon off of the flame sensor and cleaned out the burner box. Checked the pressure switch for clogs and tested the drain line with several bottles of water to ensure that there are no leaks or clogs. Replaced the air filter size 16x25x1 and checked all electrical connections to ensure that they are secure and in good condition. Performed humidifier service for a healthy climate powered humidifier. Removed and replaced the old #35 water panel. Cleaned out the housing and drain line. I powered the system back up and called for heat. Took a combustion analysis test and received the following results, o2 is 8.1% and the co levels are 8ppm. The inducer motor and blower motor amp draws are within normal range. Tested the humidifier for proper operation and leaks. Both systems are operating properly at