The U.S. Attorney's office in Washington has been investigating - so far without finding any evidence of criminal wrongdoing - whether Greg Schneiders, a close aide to President-elect Jimmy Carter, illegally collected unemployment benefits during 1975.

John W. Karr, Schneiders' attorney, said yesterday that Schneiders collected just under $6,000 in unemployment compensation from December 1974 to December 1975, at the rate of $117 a week, the maximum allowed by law.

Schneiders was hired as a salaried Carter aide in January, 1976, and rose to become one of the new President's most trusted personal aides. He was expected to be named Carter's appointments secretary, but withdrew from consideration last week after an FBI check of his background documented a history of bad debts.

During that background check, FBI agents learned that Schneiders was running a corporation while collecting the unemployment checks. Since it would be illegal to receive a salary from a business while drawing unemployment, the matter was routinely referred to the U.S. Attorney's office here.

Sources familiar with the investigation said yesterday however, that no evidence of such illegality has been found.

Karr said that in late 1974 Schneiders did set up a firm to sponsor conferences for restaurant owners. He said his client received no income from the corporation, known first as American Conference Associates, Inc. and later as National Conference Associates, Inc.

"The idea was to share some his his experiences, and grief, about the restaurant business with those who would pay to hear it," Karr said.

Schneiders started the new venture with a $5,000 loan from his mother, Karr said, and held two conferences. The first was at the L' Enfant Plaza Hotel in Washington in June of 1975, Karr recalled. The second was in Great Gorge, N.J., in the fall.

People paid $200 each to attend the conferences, Scheidners paid himself only to cover expenses for putting on the meetings, Karr said.

It was while he was drawing unemployment in 1975 that Schneiders first met Jimmy Carter, at a small fund-raiser in Boston in July.

Shortly thereafter, in July or August, Karr recalled. Schneiders spent two days in Buffalo doing advance work for Carter. Later that fall he helped organize a fund-raiser for Carter in Annapolis. These were the only times Schneiders did volunteer work for the candidates during the period he was drawing unemployment, the attorney said.

Schneiders' new business, advising resatauranteurs, was not successful, Karr said. "He lost the money his mother had loaned him. He never received any income from the corporation."

In fact, Karr said, it is doubtful that Schneiders filed any federal or D.C. tax returns for 1975 because he had no taxable income that year. An official of the District of Columbia revenue office said he could find no record of Schneiders having filed a D.C. return for 1975.

Schneiders' financial difficulites before he joined the Carter campaign also are illustrated by two other incidents involving his struggling American Conference Associates.

Washington attorney Benjamin Cabell said Schneiders still owes him $848 for legal work in setting up the corporation.

Carol Santos, the landlord of Schneiders' 1018 North Carolina Ave. SE. residence said that a check drawn on the account of American Conference Associates was one of several of Schneiders' rent checks that bounced.

The FBI background check showed that Scheiders' restuarant businesses also had trouble with bounced checks. Employees have reported that their paychecks sometimes could not be cashed because the company accounts insufficient funds.

In addition, some employees have complained that money withheld from their checks for a group health insurance plan was not paid and as a result they were not covered.

Schneiders also has been sued in small claim court three times, has owed Georgetown University more than $2,000 in tuition fees since 1969, and got in a scrape with the city health department in late 1973 for keeping his Capitol Hill pub, Whitby's open after it had been ordered closed.

Scheniders was in North Carolina yesterday for the wedding of another Carter aide and could not be reached for comment. He was married himself just nine days ago, on New Year's Eve and has been honeymooning in the Virgin Islands.

Karr said yesterday that Schneiders spent part of his wedding day with him at the U.S. attorneys office discussing the unemployment compensation matter.