I received a call the other day from the State Department saying they were doing a security check on Ambassador Averell Harriman, who is being considered for a five-week appointment as a member of the U.N. Conference on Disarmament. Harriman served seven presidents in every sensitive position this country has ever dealt with but still had to be cleared by State for this job.

At first I thought it was a joke so I called back to see if they were serious. It turned out they were. The man in charge was not there so I never had an opportunity to give my opinion as to whether Harriman was a loyal American or not. The next day I went out of town so I couldn't get back to the security man, but the time lag got me to thinking.

Should I go out on a limb and say that as far as I know Harriman could be trusted, or waffle on the issue in case there was a skeleton in his closet that I didn't know about? If I vouched for the former governor of New York and they suddenly found a bunch of microfilm in his pumpkin patch, it could hurt me when it was my turn to be considered for an ambassadorship to a UNESCO conference in Paris.

If you looked carefully at Harriman's record there is a lot there to make you suspicious. During World War II he was ambassador to the Soviet Union and knew Josef Stalin personally. That alone should not compromise somebody, but later he also turned up at Yalta with Roosevelt, Churchill and Stalin.

Then there was the Marshall Plan which Harriman headed right after the war. It's true he did get Europe back on its feet, but this easily could have been his cover for keeping up his contacts with many socialists who were vying for power at that time.

Money never seemed to a problem as far as Harriman was concerned. It's true his father left him a small trust fund of over $100 million, but that certainly doesn't explain the lavish dinner parties he threw in Paris. There had to be money coming from somewhere else. I never found out where.

I lost track of Harriman when he became governor of New York state, though I heard through the grapevine that he was still keeping up his relationships with the Soviet leaders.

Then it was back to Washington where he was involved in working out a deal in Laos and becoming a close adviser to President Kennedy, particularly in his dealings with Khrushchev. At the time none of us thought anything of it, but when I looked back on it the pieces of the puzzle started to fall into place. Harriman was for some kind of peaceful coexistence with the Russians, arguing that war was unthinkable, which we now know was the straight Commie line.

As if that weren't enough Harriman was sent by President Johnson to meet with the North Vietnamese and arrange a peace conference in Paris. He sold out this country's interests by insisting on a round table instead of a square table, which many people still swear wrecked the talks.

Secretary of State Cy Vance worked with Harriman in Paris, never realizing that Harriman pushed for the round table on direct orders from people who felt a square table would put the United States at a great advantage.

The more I thought about it, the more I decided that I couldn't give the ambassador a clean bill of health. I was eager to get back to the State Department security people and tell them of my suspicions, but by the time I returned from my trip there was a message that Harriman had already been cleared.

Apparently all they asked of his neighbors was if Harriman drank and whether they knew anything about his sex life. He came out okay on both counts, but what do neighbors know? In 1922, when he was playing polo, there was this girl who lived in Oyster Bay and . . .