Federal agencies will begin an office crackdown this summer on workers who owe, and have refused to pay, Uncle Sam money they borrowed to finance college of technical school training.

A spot check by Health, Education and Welfare showed that there were 344,000 federally insured guranteed student loans in default earlier this year. A computer matchup indicated that at least 6,700 of the loans had been made to people who are now on the federal payroll.

HEW administers the student loan guarantee program. Officials estimate that the average uncollected debt among federal workers ranges between $1,100 and $1,500. Many of the former students now work for the government in the Washington area.

The new government program aimed at collecting loan defaults from civil servants will involve personnel offices in every agency. After identifying the employe, his or her location and office, and the amount of the default, personnel officers or their designees will counsel employes. They will be advised of the obligation and agencies will try to work out voluntary repayment programs - with payments as low as $30 a month.

Employes who do not respond eventually will be subject to various kinds of disciplinary action. In some agencies, like the Internal Revenue Service, which has a strict employe debt code, they could be fired as well as prosecuted over money owed.Federal officials say that, to avoid embarrassing employes, immediate supervisors will not be used for counseling, or even be informed that their workers owe money to the student loan program.

Previous federal attempts to collect loans from employes and private citizens have not been either vigorous or successful. In many cases, HEW said, the majority of loan defauters had never received a bill - prior to this year - for money owed.

Some people, officials said, might not even be aware that they owe the money, even though they did sign loan agreements when they were students. "It is possible that people who don't read what they sign don't even know they owe anything," an HEW source said.

Fortunately for the loan program, 87 percent of the people who borrowed money through the government-guranteed program paid it back. But the 13 percent who have not paid anything back owe an estimated $350 million to $450 million.

The new give-at-the-office program will not begin until late July early August. Meantime, the government is hoping that employes who do owe money will make arrangements to begin paying it back. HEW's Office of the Secretary, under the Operation Cross-Check Program, is the place to inquire about student loans defaults.

Veterans Preference: Powerful veterans group have persuaded Rep. James M. Hanley (D-N.Y.) to speaker an amendemtnt to retain the lifetime hiring and firing preference that military veterans enjoy in government. The Post Office-Civil Service Committee begins final action this week on President Carter's civil service reorganization plan. A key element of the changes is elimination of veterans preference, which, its critics say, discriminates against women and minorities.

Hanley's support is a big victory for the veterans groups. He's in line to take over the committee next year. His endorsement of the retention of VP could persuade some fence-sitters to come down on the side of the powerful veterans lobby when the committee votes on reform.

Dan Kerney of Boston and Robert Harnage of the Atlanta region have been elected national vice presidents of the American Federation of Government Employees. Kerney knocked off Phil O'Donnell, who took the job from him two years ago. Harage defeated incumbent Forrest Wooten.

In other AFGE regional races, incumbents Royal Sims and Glen Peterson were reelected in the Philadelphia and Dallas regions.

Civil Service Commission's regional directors are in town for one of their twice-a-year visits to Washington which, beyond the beltway, is known as Disneyland East in federal circles.

Much will be said about civil service reform and the proposal for a new high-risk, high-reward job and pay system for top federal executives.