Despite President Carter's vow to make the bureaucracy more responsive and open, his signature on a June 3 memo has triggered what some federal employees are calling a classic bureaucratic snafu.

The memo said, in essence, that Carter had decided to give the Forrestal Building in L'Enfant to his energy Czar, James Schlesinger, as headquarters for the new Department and Energy, and that the present occupants - some 5,000 Department of Defense employees - should be reloacted by Oct. 1.

But officials are sensitive to the fact that Congress has not yet credited the Energy Department. Therefore, they have not confirmed the move because, they say, they cannot officially plan for an agency that does not exist.

Meanwhile, as the Oct. 1 deadline draws nearer with no clear word from above, rumors are multiplying like federal regulations, in the car pools, over lunch and in the ahllway at the Forrestal Building, which is a modern beehive completed just seven years ago specifically for the Defense Department.

One of the rumors is that 1,000 or more people currently working at Forrestal will be transferred to other states. Some workers have been anxious for weeks over the possibility that they will be expected to sell their homes, find new ones in strange cities, get packed and moved, accommodate their spouses' careers and other family needs, and do all the complicated things connected with such a move - all by Oct 1.

One Defense Department expert on buildings and moving said six to nine months would be normal planning time for such a move, rather than the three months or so apparently contemplated in this case.

"Mr. Carter does not realize the havoc he is creating," said one Forrestal worker who said he has a "large family and mortgaged house" and feels "desperate."

Joel W. (Jay) Solomon, new administrator of the General Services Administration (GSA), the federal "landlord" agency that allocates office space , was the man to whom the President's memo was addressed. The memo told Solomon to "take immediate action" to relocate the Forrestal occupants and added that "some space" should be available by the time Congress authorizes the Energy Department. That could be soon.

Solomon says only that the President has issued an executive order for GSA to "study and evaluate" the Forrestal Building for "possible use" by the Energy Department and this is being handled by regional administrator Jack Galuardi. Solomon says that as soon as any plans are developed they will made public. The question of financing, he adds, has not yet been addressed.

As for the Department of Defense, a Pentagon spokesman said. "We're in a tough position. We can't discuss it, not only with the media but with own internal audience. We have no official notification from GSA and therefore no official response."

An Air Force memo being circulated has further angered some Defense workers. It indicates that the President's June 3 memo to GSA did not reach the office of Defense Secretary Harold Brown until June 28 - a 25-day delay.

Solomon explained Friday that after he received the memo, he sent it back to the White House with a request for further study; that the memo was returned to him perhaps two weeks later, and that meetings were then set up with representatives of Schlesinger and the Defense Department as soon as possible.

The Department of Energy is expected to have around 20,000 in personnel, with some 8,000 in the Washington area, according to a White House spokesman.

Since the Folrestal Building will house only 5,000 of them, he added, it will be up to GSA to work out what will be done with the other 3,000.

Employees for the planned new Department of Energy currently are scattered in numerous agencies such as the Energy Research and Development Administration, whose functions will be combined in the new agency.

Some Defense administrators complain that the move is more a political power plan. They said it is inefficient because it would require two agencies to move rather than just one, that it would unnecessarily costly (one estimate was $7.5 million), that just moving the big computer complex at Forrestal will be complex and costly.

Some observed that the Forrestal Building is an "ideal location for a Cabinet official, right between the White House and the Capitol," and that "obviously the newest department in government needed a show place."

"Then it became a matter of political clout (with the President)," said one Defense Department official. "It seems clear as day that Schlesinger has it and the Defense Department does not."

Employees in some of the offices on the seventh floor of Forrestal, with a dazzling view of the Smithsonian Castle and a parade of marble up the Mall, say that their supervisors have told them "informally" that they will move to another part of the building between Sept. 1 and Oct. This is to make room for Schlesinger and his immediate staff, they hear.

But according to deputy assistant building administrator Don Neis, "There's no way you can move that many people in just a month." Neiss, who would be involved in planning any such move, says he is "in the dark," too.

Military employees at Forrestal are inclined to take a "good soldier" attitude toward the crash move. They may not like it, they say, but "we'll go where our commander-in-chief sends us."

Some shrug and say this move is simply a typical government approach to shuffling its employees and that the employees can alway be counted on to moan and complain. Only the continuing dearth of information in the face of what seems an impossible timetable, they say, makes it different.

But some civilians are less stiff-lipped. "I think it's a shame. The Army Corps of Engineers has been pushed around for years," said a gray-haired corps clerk in a flowered dress. (The corps, with about 1,000 employees housed in Forrestal, is one of the largest agencies there.) She and her co-workers recalled their pre-Forrestal days in a roach-and-termite-infested temporary building out by National Airport, and before that somewhere else. "Now we hear we're going everywhere from Baltimore to Indiana."

Where some Forrestal employees say they are content to pass the time starting rumors about where their agencies will go (Hawaii is a popular one), others are circulating petitions to get Congress to help block or delay the move. And they have called on their union for help.

But the national office of the American Federation of Government Employees says it probably won't take a position because the situation involved two local with opposting interests (those moving in and those moving out).

Besides, according to a spokesman, "in a case where one agency has more political clout than another, for us to get involved would be like a cop jumping between a husband and wife fight."

Meanwhile, according to James F. MacDonald, director of the Army's civilian personnel office in Forrestal, some people are refusing job offers from agencies in the building because of the uncertainty over the move.

And some workers, as a sign on a seventh floor men's room announces, are down with "the Buzzard Point blues."

Buzzard Point is a much-publicized "white elephant" office building in Southwest Washington, which was leased by GSA for federal use in 1975. Employees of several agencies have resisted moving into the building because they contend its location is isolated; it presents a high-risk of crime, and lacks parking, eating and public transportation facilities.

Though the FBI has moved some of its offices into Buzzard Point, there are spaces for about 1,000 people there, according to one official, and it seemed inevitable that some Forrestal workers would end up there. Ft. Detrick, Md., some 50 or 60 miles away, is another likely spot.

"I think Buzzard Point is where we're being sent," said a records analyst for the Corps of Engineers. "I think they won't say anything because they're afraid we'd all get up and quit. I probably would.

An administrator in the Army surgeon general's offices in Forrestal looked out his window at the pleasant view, and mixed bitterness with levity as he said, "I guess they'll just keep the moving vans circling until they find some place for us to go."