The Federal Communications Commission, responding to a federal court ruling, yesterday reopened the books on one of the most controversial broadcasting issues, whether the agency should limit the amount of advertising on children's television programs.

In a brief meeting yesterday morning, the commission voted 4 to 0 to ask for public comment on how, if at all, it should limit time devoted to children's advertising. Previous limits were abandoned as part of a general deregulation of TV advertising in 1984.

Action for Children's Television, a Boston-based group that brought a lawsuit that resulted in yesterday's move, welcomed the news.

"I think it's nifty that they are finally putting this issue on the public record," said Peggy Charren, the group's president. "Through the whole Reagan administration, all these children's television issues have been discussed in the back room."

The National Association of Broadcasters responded with a more cautionary note. "Broadcasters will certainly continue to be concerned about government intervention in commercial time practices," said Glenn C. Wright, chairman of its children's television committee. But he said the association would work with the commission to reach a solution.

ACT contends that the TV industry has stepped up advertising since the limits were dropped. Industry officials, however, deny any significant change.

"The majority of broadcasters are adhering to the old code," said Wright. In general, that called for 9 1/2 minutes of advertising per hour as the maximum during weekends and 12 minutes per hour during weekdays.

For years, the FCC imposed such limits, on the grounds that children were a special group that might be particularly vulnerable to sales pitches.

However, in 1984 the commission, in line with the Reagan administration's philosophy of deregulation, removed the time limits from television advertising as a whole, saying market forces would keep commercial time down.

In June, Judge Kenneth W. Starr of the U.S. Court of Appeals for the District ruled that the FCC did not give sufficient explanation of its decision to include children's TV in the deregulation, and he sent the case back to the commission, giving rise to yesterday's action.

The commission did not give proper weight, Starr said, to arguments that market forces do not work with children. ACT contends that children do not avoid stations with many commercials because they may enjoy the ads as much as they do the shows.

The reopening will give ACT a new forum for trying to force recognition of what it calls "program-length commercials" and it will open the possibility of banning them. These are children's shows that are sponsored by toy companies that sell dolls and figures of the show's characters and other paraphernalia from them.

Also likely to come up is the status of so-called "interactive toys." Responding to an inaudible signal emitted by the television set, the toys allow a child to shoot at pictures on the screen during a program and "interact" with the action there, in a way similar to a video game.

ACT contends that the shows function as full-length ads for the toys and that it is not fair to use public airwaves for shows that use devices that not all children can afford to buy.

Yesterday commissioner Patricia Diaz Dennis suggested that the FCC should study what the real issue is. "I wonder if the unspoken concern really is what is being advertised," rather than for how long, she said after the meeting.

Dennis said this raised questions of First Amendment rights and whether content was suitable for regulation.

She suggested that a mechanism might be created, perhaps an advisory board, to advise the broadcasting industry on what was best for children.