Did they maintenance on a high-efficiency gas furnace. During the maintenance I did a combustion test the CO level was nine and the O2 level was 19.2. I also clean the flame sensor and cleaned out the burner rack. Also cleaned out the blower motor housing. Also did an amp draw on the inducer motor and the blower motor which are both running within furnace specs. Also I poured water down the high efficiency furnace drain to make sure that the trap was not clogged and that it was draining properly. Also did a humidifier service where I wipe down the whole entire humidifier changed out the number 35 panel and also made sure it was draining properly which it was. Filter size 16 x 25 x 1. System is operating properly at this point. M#58MCB100-16 s#58MCB100—-11116.