The Arlington County Board last night stepped into a battle over the conversion of the Arlington Towers apartment complex into a cooperative and asked the developers to halt all conversions pending the outcome of a public hearing Feb. 6.

Board members cautioned tenants at the four-building, 1,655-unit complex not to put too much hope in the board's involvement. "I would not want our action to encourage tenants to think that the outcome will be any different," said Republican Board Chairman Stephen Detwiler.

In recent years Arlington has fought unsuccessfully to stem the tide of condominium conversions, which so far have claimed 20 percent or 8,000 units of the county's rental housing stock. Under Virginia law, counties have limited power to block condominium conversions and even less authority to affect cooperative conversions.

The board last night scheduled a work session later this month with Monument Associates, developers of the Arlington Towers, and representatives of the Arlington Towers Residents Association. Monument Associates bought the complex, built in 1955, last September and have set a Feb. 28 deadline for the conversion of the 432-unit Tyler building.

The residents association claims that the conversions will force many tenants to vacate their apartments. They complain that the prices for the cooperatives -- ranging from $32,000 for efficiencies to $74,000 for two-bedroom units -- present a "residential crisis of major proportions for those wishing to stay in the building.

Furthermore, the residents association charges that the developers have failed to make the kind of basic improvements that would justify luxury prices.

Annette L. Ruth, a spokesman for Monument Associates, said last night that the developers have complied with provisions of the stage condominium laws even though those laws do not cover cooperatives. Tenants in the Tyler Building were given 120 days notice and those dislocated by the conversions will be compensated under the county's voluntary guidelines for relocation costs, she said.

Ruth said it is unlikely that the developers would slow the conversion process as a result of the board's action last night. "They are paying a tremendous interest on the property. The financial clock is ticking," she said. "As far as I know, they are planning to proceed with conversions although they are amenable to working with the county."

At its reorganization meeting last night, the County Board unanimously elected Detwiler to serve as chairman for his second year in a row. The tradition in Arlington has been to rotate the chairmanship annually.

In his inaugural address, Detwiler repeated a pledge made a year ago to promote quality development in Arlington and to continue efforts to preserve affordable housing in the county.