Following a year of acrimonious debate over the closing of elementary schools, the Fairfax County School Board last week voted to impose a moratorium on secondary school closings for the next two to four years.

The new policy, which means no intermediate schools will be closed before 1983 and no high schools before 1985, was announced even though neither the board nor its staff is currently considering closing any secondary schools.

The move apparently was prompted by rumors that several underutilized secondary schools in eastern Fairfax might be closed to save money. The board last year closed seven elementary schools and recently voted to close two more this fall.

The moratorium on secondary school closings will give officials several years to study ways of keeping those schools open, perhaps by changing student-teacher ratios, school boundary lines and course offerings.

New enrollemnt projections for the next five years, including estimates based on the 1980 census, are now being prepared by school officials, but are not expected to differ significantly from last fall's projections, according to Alton C. Hlavin, assistant superintendent for facilities services.

Last fall's figures predict that secondary schools in the eastern half of the county will lose about 2,500 students, while the rapidly developing western half will gain about 2,800 students.

A $51.6 million bond referedum proposed by the school board earlier this year includes funds for three new elementary schools, one new intermedaite school, four school additions and nine renovations.

Last week, the board voted to build a second new intermediate school in the Pohick-Centreville area after pressure residents concerned about crowded classrooms. The new plan would add $10.3 million to the bond issue which, if approved by the county Board of Supervisors, will go before voters this fall.

In other business, the board was told that county residents, in a poll conducted in February, had given the schools an "awfully good report card."

The last survey of public attitudes toward the schools was in 1974. Ned Hubbell, of the Michigan public polling firm that conducted both surveys, said "The good feeling (residents had about the school system) is still there."

The 1974 poll, Hubbell said, showed that 74 percent of those surveyed considered county schools "excellent" or "good." In this 1981 survey," he added, "82 percent voiced that opinion -- up significantly."

About two-thirds of the 642 residents polled gave Fairfax teachers excellent or good ratings, and 57 percent gave principals the same marks. The lowest ratings came for the school board itself, with 44 percent of the respondents rating the board excellent or good. Slightly more than one-fourth of the residents, or 26 percent, said they didn't have enough information about the board to make any comment.

Eight out of 10 persons polled praised teachers, school curriculum and special education programs as features they particularly liked in the school system.

The biggest problems cited were student drug and alcohol use and poor discipline in the schools, which the study noted were the two areas cited as problems for schools across the nation in a 1980 Gallup poll.