The newly installed Montgomery County school board, in its first official meeting, voted yesterday to reconsider decisions to close Takoma Park Junior High School and Northwood High School in Silver Spring, two of the most protested closing actions of the preceding board.

Takoma Park, the junior high with the highest minority enrollment in the county, is scheduled to close next September, and Northwood in September 1984. Both schools were targeted for closing because of declining enrollments.

The decisions to reconsider the closings were approved by the four new members and their incumbent ally, Blair Ewing, who was elected president of the board. They were among a number of actions yesterday that reflected a shift in direction from the previous board, whose policies were a major campaign issue in the Nov. 2 election.

Other indications of philosophical change were evident in votes on issues of importance to school labor unions: The board abolished a citizens advisory committee on employe negotiations, and said it would support a change in state law to allow unions to collect dues from the nonmembers they represent.

Three other policy decisions considered central by the last board were expected soon to be targets for change: A pending ban on smoking at high schools, countywide standardized final examinations and extra grade points for students taking advanced courses.

The board approved a request yesterday by member Marian Greenblatt to ask the state Board of Education if Rosemary Hills Elementary School might be closed if its students were not transferred to as many schools (four) as proposed in an earlier plan.

In overturning that proposal -- the first time a school closing had been reversed -- the state board said the plan unfairly placed the burden of transportation on minorities. The suggestion by Greenblatt, the leader of the previous board, was made during a wide-ranging discussion of school closing and boundary decisions.

The vote to reconsider the Northwood and Takoma Park school closings was regarded as a victory for activists in those communities who campaigned throughout the past year to reverse the previous board's decisions. Parents of Northwood's 1,280 students have appealed that closing decision to the state board but a hearing examiner concluded last month that the local board acted Takoma Park parents filed suit in Circuit Court after the state board rejected their appeal.

Takoma Park supporters, in particular, have waged a long and expensive battle to keep their school open, arguing that it nurtures a diverse and integrated population (67 percent of the 370 students belong to minorities).

The board members who supported reconsidering the closings yesterday stressed that their actions did not guarantee support for the reopening of the schools, and pledged that no other schools would be closed as a result of any future decision.

The board also announced yesterday that it would hire a consultant to conduct a nationwide search for a successor to Superintendent Edward Andrews, who plans to resign in July. The board said that the consultant applicants by March, after which the finalists would be invited to meet with staff and community representatives.