The Divad antiaircraft gun had to be heated for six hours with the field equivalent of a hair-dryer before it was ready to fire during tests of its cold-weather capability last spring, Sen. Mark Andrews (R-N.D.) charged at a Senate subcommittee hearing yesterday.

Andrews also said that Divad test results showed that in subzero temperatures the gun registered readings 180 degrees off -- "hardly reassuring to your reserve units," he told Army leaders present.

"On my farm," Andrews said during the Senate Appropriations defense subcommittee hearing, "my cattle will starve" if machinery fails to work at 40 degrees below zero. He said the Divad was tested in a cold chamber at 25 degrees below zero when it experienced the failures.

"Unless the Army plans to fight only in the balmy, 70-degree temperature of early summer," Andrews said, "this implement is far from satisfactory."

The North Dakota senator and sunflower farmer also said that the Divad, which stands for division air defense, was supposed to fire 2,000 rounds before it broke down but got off only 1,354 rounds in its best performance during last year's test.

The Divad, called the Sgt. York, has the primary role of protecting troops from helicopters and warplanes but also is designed to stop thin-skinned armored vehicles with its twin 40 mm guns. The Divad is mounted on an M48 tank and uses a modified version of F16 fighter plane radar for tracking and fire control. The program would cost about $6 billion if completed.

Andrews said instead of continuing to spend $25 million a month to keep producing Divad while its problems are being addressed, the Army should halt production as soon as possible.

"There have been problems with the Divad," Army Secretary John O. Marsh Jr. conceded. But he reminded Andrews that Congress had pressed the Army to develop and produce the gun concurrently.

As for Divad's problems in cold weather, Marsh told the subcommittee that he had just been handed a note that said they had been corrected. The big problem, according to the Army, was failure to use diesel fuel designed for winter use during the subzero tests.

But "you haven't stopped" buying the Divads to correct its flaws, Andrews told Marsh. "You're spending $25 million a month buying more of these lemons."

"Senator," Marsh replied, "I'm not sure at all that they're lemons. We're convinced we're going to be able to straighten out the problems."

"How about that problem that you'd have to have a heat unit on your computer for 6 1/2 hours before it would point the guns in the right direction?" Andrews asked. "Have you got some way of solving that?"

"It's got to be one of the areas that will be addressed," Marsh replied.

"I would hope so," Andrews said. The senator then turned to Gen. John A. Wickham Jr., Army chief of staff, and asked whether he, as the nation's top soldier, felt that the Divad was ready to put in the field with the troops.

"I don't characterize the Divad as a lemon," Wickham began. "It has problems, and we are resolving those problems as we go."

"Lord knows, senator," said Wickham, his voice rising, "I've given my whole life to the military, and I'm not about to go out and buy a piece of equipment that hazards lives of soldiers. I was almost killed myself in Vietnam, and I'm as deeply concerned as you are about buying good equipment.

"If this piece of equipment does not turn out according to the specifications" laid down for it by the Army, Wickham said, "we're not going to buy it, but we're going to have to buy something else" to provide air defense against the Soviet threat, particularly helicopters armed with air-to-ground missiles.

Ford Aerospace and Communications Inc., manufacturer of Divad, has said that the gun has performed up to specifications in most areas. The Army next month is scheduled to conduct an intensive series of tests to decide whether to complete Divad procurement. Marsh and Wickham said the previous tests Andrews mentioned did not indicate the gun's true capabilities.