The Fairfax County Board of Supervisors voted in principle yesterday to hold hearings on all public housing projects proposed for the county and to forbid the expenditure of any tax funds on them until after the hearings.

The board left to its housing subcommittee the task of working out details such as when the hearings would be held and whether projects already under way--such as the controversial Circle Woods project near Fairfax City--should be subject to hearings.

In addition, the board voted to advertise the hearings in local newspapers and to require notification of any civic organizations and property owners within 1,000 feet of any proposed project.

The hearing resolution was offered by Board Chairman John F. Herrity, a Republican, and passed on a series of voice votes. The board voted last week to kill another Herrity resolution, which would have required the board specifically to hold a hearing on the Circle Woods project, where construction of 21 public housing units is slated to start in the spring. The board yesterday rejected an attempt by Herrity to revive that proposal.

Public housing proponent Supervisor James Scott, a Democrat from the Providence District who represents the Circle Woods development, said the public hearing proposal "is nothing . . . but an attempt to stop all public housing projects in the county."

Supervisor Nancy Falck, a Republican of the Dranesville District, countered that residents have a right to know when public housing projects are being considered for their area. "I cannot believe this board would go on record against holding public hearings" for subsidized housing, she said.

Board vice chairman Martha V. Pennino, a Democrat from the Centreville District, warned that the board may be taking a dangerous path, because at some stage every plan becomes controversial and some group is going to request a hearing to protest. She said that the subcommittee must work out a public hearing process to avoid that, or "we're going to throw planning out the window, I mean planning across the board."