Arrived to do a performance maintenance. Set up for combustion analysis temperature split and static pressure tests. Verified operation of all mechanical and electronic components of the furnace. Checked blower for cleanliness and to see if there is any play in the bearings. Found that the fan for heating and cooling is beginning to collect dust. Checked systems heat exchanger to ensure proper venting of flue gas. Found bacterial growth on the evaporator pan. Performed an electronic gas leak search. Verified operation of the humidifier. Found bacterial growth in the evaporator panel. Furnace and humidifier are operational at this time.