The United States has made "plenty of promises in the past, sometimes with a poor performance record," U.S. Ambassador to the United Nations Andrew Young acknowledged today to a conference here of Latin American economic ministers.

Young said that the United States has learned that "We cannot solve the world's problems, or the hemisphere's, and that 'Made in the U.S.A.' does not necessarily mean it will work in Latin America."

Instead of a "new slogan or a basketful of gifts," Young offered the Latins a piece of his own philosophy gleaned from the U.S. civil-rights movement, with a bit of the Rev. Martin Luther Kingand Jimmy Carter thrown in.

A new hemispheric relationship, Young said, "will not be the result of just more negotiation, more research and more conferences," but rather the realization of a joint "vision, a dream and a hope that all our efforts can make a difference."

While the Latins, delegates to the 17th biannual conference of the U.N. Economic Commission for Latin America, responded with contained, if polite, applause, many later privately expressed approval of the U.S. attitude. That attitude, as expressed by Young, was basically one of self criticism, combined with offers to work as a philosophical, though wealthier, equal.

"A very interesting thing has occurred here," said a high-level Latin official. "It's a complete change from five or six years ago when you had the United States preaching hard-line pragmatism and things like inflation control to the Latins. Then, the Latins were interested in pholosophy and long-range attitudes. Now, the United States is talking about visions."

In an expansion of President Carter's promise for a "new direction" in Washington's Latin American policy, Young made the same promise as Carter to "work with you, and work hard, to find ways of uniting our common love for freedom and justice with our great need for economic development."

Tying human freedom to economic growth has become Carter's way of emphasizing his human-rights concerns, with U.S. economic support coming through better trade terms and contributions through multilateral lending institutions.

In his only direct reference to U.S. criticism of human-rights, violations, specifically in Argentina, Chile and Uruguay. Young couched his comments in economic terms.

"The great number of allegations of torture and political prisoners . . . people who have disappeared and political assassinations, cannot be a disconcerting factor in any search for unity of purpose . . . Torture and other forms of political repression are not only in violation of our own national commitment to the United Nations but are also major obstacles to economic and social change."

At least one delegation did not appear interested in new U.S. "visions." Immediately following Young's speech, the Cuban delegation existed en masse to revise its own speech, scheduled for delivery several hours later. In the printed text released following their presentation, the Cubans had apparently typed in several extra pages in which they made their own comments on human rights.

In a later press conference, Young said he had no plans to talk privately with the Cuban delegation here. "The people that I have agreed to talk to today, I just bumped into in the hall," he said, "and I don't have the slightest idea of what we're going to talk about. If I should bump into the Cuban delegate and he should ask that we get together I would be glad to get together with him. I haven't the slightest idea what we'd talk about, but I'm sure we'd find plenty."

"This is not a campaign for human rights in the sense that we're going around organizing the world against some other nation," Young said. "It's the American people themselves saying that they don't want to finance repression."

Asked if he had in mind any specific instances in which the United States had "financed repression" in Latin America, Young smiled and said: "Oh, yes. And so do you, too, so I don't need to call them to your attention."

In a final press question, Young was asked by a Cuban reporter if he did not think it unjust for the United States to refuse to buy Latin American products while trying to sell the Latins new "visions and hopes."

Young's answer: "Yes."