Nearly 100 residents of D.C. public housing projects for the elderly and handicapped confronted Mayor Marion Barry at the District Building yesterday and demanded that the city provide security guard service -- which has been missing for two weeks -- and repair air conditioning systems.

They were an unlikely band of protesters. Most were in their 60s or 70s, with gray hair the rule, and many walked with canes. They arrived in a ragtag motorcade and assembled outside the building. City Council member John A. Wilson (D-Ward 2), whose ward contains many of the housing projects, met them and led the group to the fifth-floor council chambers, explaining that he thought yesterday's sun was too hot for them.

The group settled in, sang "We Shall Overcome," and chanted for the mayor to appear. Building guards cautioned the senior citizens against making too much noise. Barry finally arrived, saying he had not known the group was coming.

The elderly and handicapped residents were protesting the city's inaction in allowing a contract with a private security firm to lapse on June 30. Since then, all the buildings have been without regular protection, with residents themselves sometimes having to man the buildings' front desks after midnight and the city's own 24-man security squad stretched too thin to provide adequate coverage.

"I was on the desk Saturday night," said an elderly woman resident of Judiciary House, 461 H St. NW, "and I had to call the fire department and the police department. A couple of drunks got stuck in the elevator. I'm just asking one thing. If I'm going to have to sit on that desk, will you please bring me a club?"

"Just give us today and tomorrow to try to work something out and get some guards," Barry told the group. He promised "our strong support in trying to solve these problems."

Robert L. Moore, director of the city's Department of Housing and Community Development, said the guard service had been allowed to lapse because installation of new electronic security systems at all the buildings was supposed to be completed by June 30. In fact, Moore said, the work will not be done until the end of July.

In the meantime, residents complain that outsiders are able to enter the housing projects at will, including prostitutes who sometimes pay tenants for the use of their rooms and bring customers inside.

Randolph Taylor, president of the resident council at The James housing project, 14th and N streets NW, said he sometimes has to work the midnight desk shift formerly handled by security guards and is afraid to challenge women entering the building late at night who appear to be prostitutes.

Others complained of air conditioning systems that either do not work or are so poorly maintained that they are ineffective.

Claridge Towers, a project at 1221 M St. NW, has been without air conditioning for more than a week because of mechanical failure. Officials told residents yesterday that it could be another week before the system is repaired.

Taylor and a few other residents sat around the sparse, threadbare lobby of The James yesterday afternoon, trying to keep cool. The air conditioning was ostensibly working, but a thermometer read 87 degrees at the front desk. Taylor said his apartment and 13 others in the building are also without air conditioning.

"The maintenance ain't nothing," said Edward Bowles, a 67-year-old retired government worker. Bowles' apartment was cool, but only because he had taken his air conditioner apart, replaced the filter and cleaned the motor himself. "Most people can't do this kind of thing," he said. "I can't do it for everybody."

"My kitchen is so hot, I hate to cook," said Genevieve Nerverson, who has to keep a fan going along with the air conditioner. "They shouldn't treat us old people like that. I thought they were going to take care of us like human beings. I'm used to something. I'm not used to some trashy place."