Arrived to do a twinned system performance maintenance. Set systems for cooling. Measured each units static pressure and measured a temperature split between return and supply air. Checked interior of the furnaces for cleanliness. Found that the blower wheels in each unit are coated in dust debris and there is bacterial growth present on each evaporator coil. Went outside and verified refrigerant levels. Verified operation of all electronic and mechanical components. Found that the capacitor in the left hand condenser is failing. Rinsed condenser coils free of debris. Spoke with homeowner about the system. Air conditioning system is operational at this time.