Complete 1 system a/c repair and preventative maintenance check. Left behind replacement filter. Tested refrigerant pressures. Tested mechanical and electrical components. Found evaporator coil to be very rusty and corroded and therefore likely to leak refrigerant. Found suction line missing insulation where it goes into air handler. Found dirty evaporator coil. Found dirty blower wheel. Found ductwork to be undersized. Found no return plenum on system, return duct is connected directly to air handler. Found electrical pitting present on main electrical switch. Found no water safety switch on system To protect the ceiling from water damage and it is therefore not up to code. Refrigerant pressures are as good as they are gonna get with airflow not being properly balanced. Due to the age and condition of the system, recommend upgrading system to a more reliable, more efficient system. The system is cooling at this time.