The future of rent controls in Montgomery County remained in doubt last night despite a vote by the County Council to extend controls with minor changes for two years.

It was unclear whether the extension will survive the opposition of County Executive Charles Gilchrist, who is likely to veto it, and if he does not, whether it will have any significant impact, since the extension won't go into effect until about two months after the current controls expire.

The present controls expire at midnight Jan. 31. If the council had mustered five or more votes for the extension, it would have gone into effect as an "emergency measure" Feb. 1, leaving no gap in coverage. But the advocates of controls were only able to get four votes, and the extension would not go on the books until sometime in April.

Last night's vote followed three hours of debate during which some council members complained they could not understand the issues at hand. Others admitted they had no idea how the current dispute over the county's seven-year experiment with rent control would end. Montgomery County is the only one of Washington's suburban counties to retain rent controls, which were widely adopted in the early 1970s.

Proponents of decontrol argue that controls inhibit new investment in housing and spur the spread of condominium conversion.

Tenants' groups expressed disappointment with the extension as passed, since there would be a two-month gap. "What's going to happen to people in between?" asked Barbara Schiller, president of the Montgomery County Tenants Association.

"I feel there's still some hope," said Councilwoman Rose Crenca, who spearheaded the effort to keep rent controls. She expressed hope that Gilchrist would withhold his veto because the bill represents "soft control" that will gradually decrease because apartments revert to the free market whenever tenants move out.

Currently about 40 percent of the county's 39,000 rental units are covered by controls. To raise rents of controlled units by 10 percent or more yearly, the landlord must demonstrate that costs have risen beyong specified levels.

The bill approved last night dropped the 10 percent cutoff point and replaced it with a "rent guideline" that would be linked to rises in the consumer price index. In setting the guideline, the county executive would be allowed to consider "any factors relevant" to landlord expenses as well.

Further confusion was introduced by questions of how the bill would be applied if Gilchrist does not veto it.

Regulations require a landlord to give a tenant 60 days' notice before instigating a rent increase. If rent control were restored before those 60 days elapsed, would a landlord be allowed to collect the increase? This issue is currently under litigation in county courts.

Voting to extend controls were Crenca, Scott Fosler, Neal Potter and Elizabeth Scull. Opposing extension were Council President Ruth Spector, Michael Gudis and Esther Gleman.

In other business, the council postponed action on a controversial bill to ban obscene performances in the county.