Heads kept turning toward the door. Waiting. You could cut the anticipation with a knife. Cap the knife.

"I've known him for years. I think Haig is all right. Now WRITE THAT DOWN," was the first remark Defense Secretary Caspar W. Weinberger made upon walking into the South Carolina Room of the Mayflower Hotel.

Weinberger and his wife, Jane, were among the first guests at a VIP reception preceding the Second Annual Washington Heart Association Ball on Saturday night. With a small group of other guests, the Weinbergers chatted and sipped cocktails before Secretary of State Alexander M. Haig Jr. and his wife, Patricia, arrived.

They got about two steps before the two dozen guests thronged around. Haig and Weinberger greeted each other, shook hands and came out cordial.

It was a diplomatic end to a week of high-level skirmishes in the administration. As Weinberger said, "The sign outside the door sums up my feelings: 'Restoration in Progress.' "

After a dinner of chicken veronique, Haig, smiling and slightly windburned from a day of tennis with Attorney General William French Smith, walked to the podium to a standing ovation from more than 400 guests, including business executives and the ambassadors of Yugoslavia, Luxembourg, South Africa and Italy.

"Some years ago, when one was plagued with a heart problem, his physician told him to slow down life, become shy and retiring," began Haig, who over a year ago had a successful bypass operation.

"Now they want you to be active and busy," he continued with a grin. "At times they even want you to be notorious and naughty . . . I want you to know I've been following the orders of my physician.

"As a matter of fact, I became secretary of state because my doctor told me to."

Haig then presented one of the evening's four honorees, Dr. Joseph V. Charyk, president and chief executive officer of Comsat, with a service award.

Weinberger spoke next, in the same vein. "It's a great honor to be in the administration with Al Haig," he said. "He's a very hard act, indeed, to follow."

Also receiving awards at the $125-a-plate benefit, which added to $110 million already raised this year, were Ewing and Muriel Kauffman of Kansas City, for their support of a program to train 100,000 citizens in cardiopulmonary resuscitation; Dr. Hubert V. Pipberger, for 30 years of pioneer work in computers and cardiological diagnoses; Dr. George A. Kelser, former head of the Division of Cardiology at George Washington University; and Dr. Benjamin L. Aaron, for his role in saving President Reagan's life last March.

Leah Chase, chairman of the ball committee, and Dr. Sander H. Mendelson, president of the American Heart Association National Capital Affiliate Inc., made the awards introductions. Then came a call from the SS Rotterdam, just departing Bermuda, to demonstrate one of Comsat's maritime communications satellites. Projected on a screen was the electrocardiogram of a healthy volunteer crew member in the intensive care unit on board.

After the crowd watched the green line representing the heartbeat on the screen, the band was struck up again, cake with raspberry sauce and coffee was served. Haig did the lindy, Weinberger left and the crowd danced their hearts out.