WASHINGTON (AP) — Some Americans will soon be able to buy a home with a down payment as low as 3 percent, compared with the current minimum of 5 percent, the mortgage giants Fannie Mae and Freddie Mac say.The new lending guidelines announced by the companies Monday are designed to help more low-income and first-time buyers afford homes. Millions of Americans lost their savings or no longer had the income needed to set aside money for a home in the aftermath of the 2008 financial crisis and the Great Recession. That has held down the sales of houses and condominiums and slowed the economic recovery.The guidelines are designed to prevent the kind of reckless lending that fueled a housing bubble and eventually triggered the recession.