Arrived to do a performance maintenance. Set system for cooling. Measured the systems static pressure measured a temperature split between return and supply air. Checked interior of the furnace for cleanliness. Found bacterial growth present on the bottom of the evaporator coil. Went outside and verified refrigerant levels. Verified operation of all electronic and mechanical components. Rinsed coil free of debris. Spoke with homeowner about the system. Air conditioning system is operational at this time.