More District of Columbia lending institutions stopped making home mortgage loans yesterday, while others postponed loan settlements in the wake of a court ruling questioning the legality of the city's mortgage interest rate law.

Two of the city's largest savings and loan associations, American Federal and First Federal, told about two dozen prospective home buyers that they would not be able to go to settlement as scheduled on more than $2.4 million in loans because of the uncertainty over the mortgage law.

In addition, other lending institutions said they would not set dates for loan settlements until the issue is resolved. Such large financial institutions as American Security Bank, National Bank of Washington, Perpetual Federal Savings and Loan, First Federal, Washington Federal Savings, Northwestern Federal Savings and Interstate Federal Savings said they no longer would make loans.

"We've told purchasers who were ready to settle that it doesn't mean we're going to not make the loan," said William Sinclair, American Federal's president. "It's just a temporary setback to make sure everything's legal."

Sinclair esstimated that his institution is delaying settlement on $2 million worth of loans for at least two weeks, while First Federal is postponing settlement on seven loans totaling $453,050. Several lending institutions said they would continue to process existing loan applications but would not make new loan commitments or accept more applications. Other lending institutions said they would still take applications and make loans to regular customers.

While lending officials debated how to deal with the mortgage funding cutoff imposed in the District this week by both the Federal National Mortgage Association (Fannie Mae) and the Federal Home Loan Mortgage Corp. (Freddie Mac), Capitol Hill legislators turned their attention to the D.C. mortgage law.

Reps. Ronald V. Dellums (D-Calif.), Stewart B. McKinney (R-Conn.) and Michael Barnes (D-Md.) and Del. Walter E. Fauntroy (D-D.C.) introduced a bill that would waive the normal 30-day congressional review of a bill passed Tuesday by the D.C. City Council. That legislation would raise the mortgage interest rate ceiling in the city to 15 percent.

The House District Committee is expected to approve the legislation at an emergency meeting this morning. Fauntroy predicted House and Senate passage by the end of next week, while some lenders in the city said they understood action could come as early as next Tuesday.

The waiver legislation would not affect any other actions of the city government, whose legislation ordinarily must await a congressional review period before they can become law.

Without the special legislation, Fauntroy said the review period for the mortgage rate ceiling could extend to January or beyond because of holidays, weekends, and other days on which Congress does not meet.

Fauntroy said he offered the legislation after consulting with D.C. Mayor Marion Barry and the City Council, 10 of whose members signed a letter to Fauntroy on Tuesday asking Congress to waive the normal review period.

The conflict over the mortgage law originated with an Oct. 19 decision by Superior Court Judge George H. Revercomb that invalidated the city's moratorium on condominium conversions. Revercomb said the city could not enact the same emergency legislation more than once, as it had done on the condominium issue.

Although that ruling did not deal with the emergency mortgage interest rate legislation that the council had passed twice, Fannie Mae and Freddie Mac officials concluded this week that there was sufficient doubt about legality of the city's mortgage law to warrant an immediate cutoff of all of their mortgage financing in the city.

Together, the two lending institutions bought $84.4 million worth of mortgages from D.C. savings and loans and mortgage banking firms in nine months of this year. Fannie Mae and Freddie Mac together provide the single largest source of mortgage money here.

The permanent 15 percent rate ceiling passed this week by the City Council would take the place of the emergency ceiling, also 15 percent, as soon as the congressional review period is waived or the 30-day review period is completed. c

Although several lenders predicted yesterday that the mortgage loan crisis would be short-lived, the consequences for at least one group of buyers may be more serious. Tenants seeking to buy a four-unit Northwest Washington apartment building were supposed to go to settlement yesterday, but at the last minute were told they could not do so because of the disruption in the mortgage market, according to their lawyer, Benny Kass.

He said that another buyer is also interested in the property, which he declined to identify, and that the tenant group faces the possibility of losing the building if the second buyer can somehow produce the cash to quickly buy the apartments.

While American Federal and First Federal postponed scheduled settlements because of the uncertainty over the mortgage law, several other lenders said they intend to go ahead with their settlements.

"There are lots of times when you have to take some business risk, and that's what we're doing with poeple we've made commitments to," said Robert Barton Jr., Interstate Federal's president.

James Harris, president of Washington Federal Savings and Loan, said his institution has 47 loans in the District totaling $2.3 million scheduled for settlements, mortgages which it had planned to sell to Freddie Mac.

"Our advice from our attorneys is don't close the loans," he said, adding that the S&L nonetheless would go ahead with the settlements.

Asked why, Harris replied, "Somebody's got to make a management decision."

Harris and other lenders said they feel it would not be fair for them to postpone settlements when the prospective borrowers had nothing to do with creating the legal problems over the mortgage law.

While Washington Federal plans to go to settlement on the 47 loans, Harris said the S&L has committed another $3.8 million in construction loans to various D.C. builders. Those loans are contingent on their resale to the Federal House Loan Mortgage Corp. Harris said these loans would be delayed until Federal Home Loan Mortgage Corp. (Freddie Mac) starts lending money in the District again.