Secretary of State Cyrus R. Vance flew to New York yesterday to renew U.S. efforts to get South Africa to agree on United Nations-supervised elections in Namibia and avoid a confrontation over economic sanctions that would present a painful choice for the Carter administration.

The choice is already creating fissure lines within the administration, where U.N. Ambassador Andrew young and some other officials are arguing that Washington should telegraph its support now for a package of limited economic sanctions against South Africa if the U.N. plan for a Namibia solution is blocked, according to authoritative U.S. sources.

Vance and President Carter are reported to be extremely reluctant to back any program of sanctions, which they apparently see as an ineffective tool in moving Pretoria, and they have not outlined an American plan for using sanctions.

Vance has kept on his desk for more than two months a comprehensive review paper that details global and selective sanction possibilities. According to two well-informed sources, he has not ordered any policy option paper on sanctions.

Abruptly canceling his Washington schedule, Vance met yesterday with South African foreign minister R.W. (Pik) Botha at the United Nations for another discussion of South Africa's refusal to call off unilaterally scheduled elections in the disputed territory, now set for Dec. 4.

The U.N. Security Council has denounced those elections as illegal and is demanding that South Africa return to a U.N. schedule for elections in Namibia, also known as South West Africa, which came through a League of Nations mandate in 1920.

South Africa withdrew on Sept. 20 its acceptance of the original U.N. plan for independence and elections for Namibia. It asserted that U.N. changes in the plan would give unfair advantages in the election to the South West African People's Organization (SWAPO), the black guerrilla group that has waged a low-level insurgency against South African troops for nearly a decade.

No details of Vance's discussions with Botha were disclosed, but informed diplomatic sources predicted prior to the session that Vance would stress Washington's desire to establish a better relationship with Pretoria and the impossibility of that happening unless the Nambia dispute is resolved.

In October, Vance carried a personal invitation from President Carter to South Africa's new prime minister, Pieter Botha, to visit Washington. The invitation was reportedly conditioned on South African cooperation in Namibia and Rhodesia.

After meeting with Vance yesterday, Pik Botha (who is not related to the prime minister) postponed a scheduled afternoon meeting with U.N. Secretary General Kurt Walheim in order to report home and apparently seek new instructions, according to diplomatic sources.

In two hours of talks earlier in the day, Waldheim sought clarification from the South Africian on two key questions: the status of the terrotorial authority that is to emerge from the Dec. 4 elections, and a commitment from Pretoria to let U.N. troops begin arriving in Namibia immediately after the elections. Waldheim is expected to report on the response before a scheduled Security Council meeting on Namibia Thursday.

State Department spokesman Hodding Carter declined to rule out the possibility that the United States will support sanctions if the Namibia dispute is not resolved. Responding to questions at the daily press briefing, Carter said a vote on sanctions would not be necessary if Waldheim made progress.

Young, a long time political associate of President Carter as well as his U.N. ambassador, publicly raised the prospect of limited economic sanctions against South Africa on Nov. 13, when he told a meeting of the Foreign Policy Association in New York:

"I think it is possible to apply sanctions that would not hurt black workers at all, and wouldn't hurt the white workers either."

Young went on to indicate that he felt the "blanket" kind of economic sanctions applied to Rhodesia would probably not be effective against South Africa.

In private, Young is known to have suggested in detailed conversations with other diplomats at the United Nations that the administration is leaning toward a plan that would lead to a three-month cutoff of all airline flights into and out of South Africa. The U.N. administered cutoff could be lifted or reimposed depending on progress on Namibia.

This plan is among the possibilites sketched in the comprehensive review, U.S. officials confirm, but these same officials adamantly insist that it is not under active consideration by Vance or the White House now.

Some of Young's foreign colleagues at the United Nations suspect that he hopes that raising the spectre of a relatively small scale but symbolically important airline embargo will push the South Africans toward settling on Namibia before a U.N. vote is necessary. Others feel, however, that by becoming identified with the sanctions issue now, Young may be hoping to maintain his credibility with Africans and black Americans even if the administration ultimately does not support sanctions.