AC system is not adequately cooling house. Did a complete thorough evaluation of system. Getting a 20° temperature split between supply and return, static pressure is a little high. Inspected ductwork, found supply Plenum leaking cold air into attic and ductwork is undersized for 3 ton air handler. Advised client to replace all ductwork in attic and add transfer Return for bedroom. Client approved recommendations and we will be replacing all ductwork, install date is TBD.