Four acting department heads were named by Los Angeles Mayor Tom Bradley Wednesday to fill top-level City Hall vacancies. In each case, the city is conducting a search for permanent executives. Rodney Punt, assistant general manager of the Cultural Affairs Department, replaces Fred Croton, who resigned under fire. Ed Rowe will take over the Department of Transportation for recently retired Donald Howery. Harreld Adams replaces Doug Ford at the Community Development Department. Faye Washington, a City Council legislative aide, replaces Dennis Jackson, who resigned as head of the Department of Aging.