After years of battling to keep their apartment complex - the city's largest concentration of moderately priced rental housing west of Rock Creek - from being converted into everything from condominiums to a diplomatic enclave, the 600 families of McLean Gardens have been notified that they must vacate their apartments by Sept. 1.

In notices delivered Thursday afternoon and yesterday, the CBI-Fairmac Corp, which owns McLean Gardens, told tenants that it will discontinue use of the unit for housing for at least six months after they are vacant.

"It's almost like the death of a family," said James W. McCabe, chairman of the Association, who has seen several attempts by the Gardens' owners to convert the rental complex during his nine years as a tenant there. "You expect it to happen, but even when it does, it's like a kick in the teeth."

McCabe and other tenants said they plan to fight to proposed evictions.

"I fully intend to stay," McCabe said. "We've beat them every time we've had anything to do with them. The next time we lose will be our first loss. It also will be our last, unfortunately."

The eviction notices did not say what CBI-Fairmac a subsidiary of Chicago Bridge and Iron Works, plan to do with McLean Gardens after the six-month period. The low-density apartment complex is on 43 acres of gently sloping land between Rodman and Newark Streets, 38th and 39th streets, NW, a few blocks from the Washington Cathedral.

Howard Friedel, director of management and operations for CBI-Fairmac, insisted in a telephone conversation yesterday that the corporation "really hasn't considered anything other than discontinuing rental use" of McLean Gardens.

Friedel declined to answer whether the company had lost money on the apartment complex, where rents range from $216 a month for some two-bedrooms.

But CBI-Fairmac Corp, which bought Mclean Gardens in 1972, and previous owners of the complex have had several massive redevelopment plans years, all of which have been fought vigorously, and so far sucessfully, by the tenants.

In the early 1970s, plans were announced for a $160 million complex of apartment and commercial construction for the McLean Gardens site.

In 1974, CBI-Fairmac told tenants it had decided to convert their units into condominiums.

In 1976, the corporation proposed demolishing the Gardens to make way for a $150 million deplomatic enclave with apartments, shops, international boutiques, and embasis and chanceries.

At least part of that most recent plan may now be impossible, however, under the new National Capital Planning Commission chancery and embassy plan. Under that plan, which now is before the D.C. Zoning Commission, Mclean Gardens is not considered an acceptible site for chanceries in Washington, according to a planning commission spokesman.

R. Robert Liniwes, soning attorney for CBI-Fairmac, said yesterday that he has no knowledge of future plans for McLean Gardens.

"All I know is that they're exploring all different kinds of avenues. They've just made a decision that they don't want to rent anymore," Linowes said.

CBI-Fairmac also owns Fairlington Villages, a low-rise massive condonminium complex in Airlington and Alexandria that once contained only government -built rental housing, like McLean Gardens. McLean Gardens was built in 1943.

McLean Gardens has about 725 apartments, but only 600 of them are currently occupied, Friedel said. He acknowledge that recently the company has not been renting apartments as tenants left.

The residents association surveyed each building in the complex recently, and found that there were 100 vacant apartments, some of which had been unoccupied since June. That means a loss about $27,000 a month to CBI-Fairmac, the association said.

The tenants plan to meet Tuesday to discuss strategy. They also plan to meet with City Council members, according to Ann Garfinkle, their lawyer.

One Washington apartment owner contacted yesterday about possible plans for McLean Gardens said he would predict that CBI-Fairmac would level the complex and build single family houses.

"I know they've spent millions in planning and remodeling that place," the apartment owner said. "All they got was a lot of hassels from the tenants and the citizens associations. And I really don't think the place is adaptable for condo use."

Phil Medelson, an officer in the McLean Gardens residents association, said McLean gardens houses a mix residents - about one-third elderly, some students, and many young professional singles and couples.

"The owners may have some whole new redevelopment plans for McLean Gardens," Mendelson said. "By getting red of the tenants, they think they're getting rid of their first line of opposition."

Cathryn Shovlin, who has lived at McLEarn Gardens for 35 years, said of the planned evictions, "I just think it's awful. I couldn't sleep last night after I got the notice. How can I fight it?"

In its notice to tenants, CBI-Fairmac said they will provide moving and relocation aid to tenants, and additional help to elderly or handicapped residents.

Polly Shackleton, whose City Council ward includes McLearn Gardens, said yesterday, "I am very, very unhappy and concerned" about the planned evictions. Shackleton said that by sending out eviction notices this week rather than later, CBI-Fairmac falls under current rent control regulations, rather than the new rent control law which she said may go into effect next week. Shackleton said the new rent control bill mayhave created greater barriers to the evictions.