House-Senate energy conferees returned from a 10-day recess yesterday still in no mood to make the decisions they face.

Rep. Al Ullman (D-Ore.)., conference chairman, told the members that after two weeks of talk it was time for them to start seeking a compromise on the "central issue" of the bill, the House-passed tax on crude oil and what to do with the revenue it would generate.

But the conferees spent the afternoon simply repeating their differences, like two wrestlers warily circling without touching each other.

President Carter proposed taxing up the price of domestic crude oil to world levels to cut consumption and rebating the revenue to consumers to avoid depressing the economy. The House generally approved this. The Senate rejected the tax but approved a long list of production and conservation incentives in the form of special tax cuts.

Sen. Russell B. Long (D-La.), leader of Senate conferees, has made it clear that his aim in the conference is to accept the crude oil tax if the House will accept his incentives for industry. A number of young House liberals have threatened to vote against the final version of the bill if Long has his way.

Ullman said the oil tax is crucial to the energy-saving plan, because it would wipe out artificially low prices that encourage use of oil.

Long replied. "I could vote for the crude oil tax provided the revenue is used for more production; otherwise not." He predicted the Senate will not vote for the crude oil tax unless "there is something in it for substantial additional production."

Rep. Thomas L. Ashley (D-Ohio) pointed out that the House bill already provides substantial incentives in the form of higher price for newly discovered natural gas and oil.

On Thursday and Friday the tax conferees will work on House-Senate differences in the Social Security bill. The first major energy tax decision apparently will not come until next week at the earliest.

Conferees on the non-tax parts of the bill made progress yesterday in compromising differences on the federal role in ordering electric utility systems to be tied together to conserve energy.

The conferees tentatively agreed that the government could on its own initiative order interconnections - the Physical connection of transmission facilities - to move power from one system to another.