Defending his character before about 40 citizens last night, Cambridge mayor angrily said it was not his fault that he was overpaid more than $30,000 from the city during the last three years.

The city council voted, 9-0, to send the matter to the council's ordinance committee to resolve the legal questions surrounding the overpayment.

Mayor Kenneth E. Reeves '72 called on city and school committee officials to clarify what Councillor William H. Walsh described as "a major foul-up."

"I didn't call up anybody to ask them to pay or not pay me. This is not a job that you take because of the money," Reeves said last night.

Reeves admitted Oct. 3 that he received a weekly stipend, totaling $13,000 a year, for his job as chair of the school committee, even though the mayor's salary, now over $44,000 annually, had been adjusted six years ago to include that stipend.

A table of mayoral salaries over the past 10 years was released by City Manager Robert W. Healy yesterday, showing that the problem began in 1988.

Halfway into the meeting, the mayor moved to suspend the rules of the council and to summon four city and school officials to testify on how the confusion arose.

While no council member has openly accused Reeves of ethical impropriety, several questioned last night how he could not have realized the overpayment.

But Reeves defended himself by saying his salary was directly deposited into his account. He said that he had thought the salary discrepancy represented refunds from taxes he paid on his city-owned car.

"I had no idea how much of its value would be taxed," Reeves said. "Either you believe that or you don't, but that's what happened."

Still unanswered, however, is the question of whether the paycheck stubs mailed to Reeves every week clearly indicated two separate origins--City Hall and the school committee. Reeves refused to comment last night.

School committee officials testified that the committee was never sent a copy of the council's 1988 ordinance raising the mayor's stipend.

Healy said a series of overlapping laws led to the overpayment. In 1983, the seven-member school committee voted to grant each of its members an annual stipend of $10,000. The following year, the city council decided, to award the mayor an additional $1,000 for his service on the school committee.

No attempt was made, Healy said, "to equalize the school committee pay and the mayoral pay."

"I guess we can't expect or require that everybody read all of the ordinances of the city of Cambridge and familiarize themselves with them," Healy added.

Several councillors disagreed.

"As an elected official, I am charged with a knowledge of the ordinances of this city. I cannot accept that explanation," said Councillor Kathleen L. Born.