Defense Secretary Caspar W. Weinberger, in his first administrative reaction to the Senate vote to freeze the military budget for fiscal 1986, recommended yesterday that Congress reduce contingency accounts in the defense budget rather than cut weapons programs.

He listed $4 billion in cuts from the fiscal 1985 budget that could be credited to fiscal 1986 to avoid cutting into vital military programs. This would "reduce the likelihood" that the Defense Department will have to ask Congress later this year for supplemental fiscal 1986 funds, he said.

The Senate voted last week to freeze the Pentagon's fiscal 1986 budget at its current level, after allowing for inflation, and to raise the total by 3 percent plus inflation in fiscal 1987 and 1988. Weinberger has studied the impact of the Senate action, the Pentagon said in a news release, and has concluded "that the new budget levels cannot be accommodated without seriously impacting the defense program."

Under the Weinberger offer, $1.6 billion would come from the surplus in this year's contingency account to cover inflation; $1.5 billion from money set aside but not obligated to contractors, with $1 billion of that amount in procurement and most of the remainder in research; and $900 million in cash kept in various funds to pay bills.

Several influential members of Congress have complained that the Pentagon has overestimated inflation and has held on to the extra money set aside for this purpose. Weinberger, by offering funds from the inflation account, may be trying to mute this criticism.

The Pentagon said Weinberger recommended using the $4 billion "to minimize program stretchouts, thereby avoiding additional future costs from uneconomical buys; to avoid unnecessary readiness cuts in areas such as spare parts and support equipment, and to finance essential elements of compensation and quality of life programs."

Yesterday, in a speech in New York to the Sons of the American Revolution, Weinberger said, "Those who would have us do without modern equipment and make do with cheaper, less sophisticated models that we know would be inferior to the Soviets' have failed to add two things to their calculations: the quality of the Soviet equipment and the value of human life."