A Dayton, Ohio, bank has given Antioch University trustees until Monday to come up with more than $1 million to bring all defaulted loans up to date, or the bank says it will liquidate the school's endowment fund.

Moreover, the school's financial vice president predicts an operating deficit this year of somewhere between $1 million and $1.1 million, and the school is open only because employes have agreed to work without pay.

Further, Antioch needs an additional $506,000 just to keep its Yellow Springs, Ohio, campus operating with a skeleton staff over the summer.

Yet Antioch trustees in their annual meeting here yesterday were cautiously optimistic that, despite it all, the school would meet the latest crises "with a little creativity." They were confident the school's scant $557,000 cash on hand will satisfy the bank and cover their overdrafts. And they were hoping that tuition and the generoisty of alumni will get them through the summer.

But what is really worrying Antioch officials is the future, because it is apparent that even if they weather the latest financial storm, the school cannot continue to operate on a budget reminiscent of the city of Cleveland's.

Antioch board members this week-end will be deciding what can be summed up as three plans: a "short, short-term" one to meet the immediate crisis - the bank default - on Monday; a "short-term" plan to get them through the summer; and a "long-term" plan for the future.

And since most board members agree that Antioch will somehow meet the two short-term crises, attention now will focus on Antioch President William M. Birenbaum's long-range plan to keep Antioch operating past September.

Birenbaum's proposal as submitted to the board yesterday is a 15-point plan that, true to Antioch's reputation, combines a number of innovative ideas. Among them:

The convening of a constitutional convention of students, faculty and administrators from across the country to develop a plan for the future of liberal education.

And including in the curriculum courses on subjects like "the utilization of staff and faculty" and "the economy of the college," to prepare for the convention.

The Antioch board will also have to address the key question of centralization versus decentralization.Antioch has branch colleges in nine cities, including the law school here, and the main campus at Yellow Springs.

The Yellow Springs campus has always been the big money loser - this year operating with a $1.3 million deficit since that campus has most of the university's fixed costs, such as pensions for retired faculty and maintenance costs.

But some of the other campuses are breaking even, like the law school which financial vice president Dudley Woodall predicts "will be balanced for the first time in living memory." One proposal for board will vote on today will determine how much autonomy to give each campus, and how much each campus will have to subsidize Yellow Springs.

One plan would mandate that Yellow Spring's budget never be in excess of 20 percent of its tuition revenue. If adopted, that would make Antioch one of the few colleges in the country supported primarily from tuition payments. Tuition currently is $6,600 per year.

Whatever plan emerges from today's final meeting, one thing is clear - Antioch must do something to stay financially afloat. As board chairman Douglas Ades said, "This is the toughest one ever. We've got all the marbles on it. It could be buried today. We are close to being where people in Alcoholics Anonymous get before they know they need help."

He added, however "The place is not going to die."