Never again will Metro buy buses with their windows permanently sealed shut, Metro board members agreed yesterday.

Air-conditioning units on too many of the transit system's 158 newest buses are not working, turning the vehicles into rolling sauna baths, board chairman Jerry A. Moore Jr. complained.

"I think it is absurd that we got caught in this situation," board member Douglas N. Schneider Jr. declared, referring to a situation in which Metro seemingly had no choice last winter but to place an order for sealed-window buses.

Nobody disagreed when Schneider said Metro should boycott similar purchases in the future. Metro had delayed its purchase decision for two weeks because of concern over the sealed windows.

Although no American manufacturer produces full-sized transit buses with windows that can be opened for natural ventilation, Moore said they are avaiable from Canadian and European sources.

Much of yesterday's board meeting was devoted to a litany of complaints about the 158 new buses.

Of these, 115 were made by General Motors using a new advanced design on a single four-wheel chassis. The other 43 are of German design and bend in the middle, accordion fashion, as they go around turns. In the trade, they are called articulated buses.

Moore asked Richard S. Page, Metro general manager, to explain a report in The Washington Post that a staff official had ordered the routing of articulated buses with working air conditioners on the Connecticut Avenue line while omitting such a requirement on Benning Road.

Of 36 articulated buses dispatched each day (the other seven are kept as spares), five are assigned to trips that include both Connecticut Avenue, in a predominantly white area, and Benning Road, which is predominantly black. The other 31 run only on Benning Road.

Page confirmed the details of The Post's account, saying there was "no question that there was a mistake within the staff organization of Metro . . . an oral instruction was misinterpreted by the daytime supervisor (at a Metrobus garage), and he posted a handwritten memo."

Thomas S. Trimmer, the director of bus services who gave the oral instruction, was not called upon to give his version.

Metro's policy, Page said, is to spread buses with broken air conditioners evenly around the system. "We have a nondiscriminatory policy, we have a nondicriminatory practice," Page declared. "I am sorry for the confusion."

Moore also said he had received numerous reports of buses that stalled because they ran out of diesel fuel. Trimmer said he was not aware this was a big problem.

But Trimmer confirmed Moore's explanation that the air conditioner motors on the articulated buses can cut off when the contents of the vehicles' fuel fall too low.

Bus tanks are too small to hold enough diesel fuel for a full day's trips, Trimmer said, so the vehicles must be returned to the garage for a fill-up at midday.

John P. Shacochis, another director, complained about the tinted windows on the new General Motors buses. They are tinted such a dark gray to prevent sun glare, Shacochis said, that passengers riding at night cannot see out and are afraid they will miss their stops.