It will be necessary to back flush the cooler through the Cooler Outlet in order to flush out any built up debris. â¢ The location of the Cooler Inlet and Outlet Hoses described in this bulletin determines the direction of. transmission fluid flow through the cooler. â¢ The Inlet and Outlet position varies from model to model, and you must identify the location of the Cooler. Inlet and Outlet to successfully perform the cleaning procedure.