Don't fall for the line that millions of dollars worth of free college scholarships go unclaimed every year. They don't. Yet some fee-charging college-aid services tempt you with that enticing "fact" to get your business. They imply that if you send them money, they can tap you into a continuous current of hot- and cold-running scholarship dollars.

Some college aid does indeed go unclaimed. But most of the "missing millions" are merely unused employe tuition benefits, according to Arthur Marmeduke, director of the California Student Aid Commission (CSAC).

Many corporations offer to pick up part or all of their employes' tuition bills for various types of studies and, without doubt, much more of this money is available than actually is used. As much as $7 billion may remain on tap for employes who want to take courses for job advancement or personal pleasure.

But this leftover money is not available to the general public. It's reserved for employes of the corporations in question.

Therein lies the deception in all the ads that talk about millions of dollars worth of unclaimed scholarship funds. To imply that, rightly directed, you could get a piece of this corporate largess is to raise false hopes.

Many other private sources of aid do exist that are open to the general public. But with a few exceptions, the grants tend to be small ones. And it's an open question whether a fee-charging college-aid service can even put you in touch with these.

In a study of their effectiveness, the CSAC surveyed more than two-dozen computerized college-aid services that offer to help find little-known or unclaimed scholarships. You fill out a form about personal interests and background and send in a fee of perhaps $20 to $50 or more. You get back a computer printout listing 20 to 40 sources of scholarship funds -- complete with address, general qualifications and size of grant. The computer is supposed to have pinpointed scholarships that you are uniquely qualified to receive.

As part of the CSAC investigation, 15 Los Angeles high-school seniors applied to 30 computer-search firms for help. They received their printouts, listing dozens of scholarships, and applied for them all.

What happened? Nothing. None of the students got scholarship offers as a result of the material they received.

In a majority of cases, they didn't even get a reply from the scholarship sources they tried to contact. In other cases, they learned that the scholarship no longer was available, or that they were ineligible for it.

Similar results were reported by the Illinois Association of Student Financial Aid Administrators, after a study of three scholarship-search agencies operating in that state. In 1982, the University of Santa Clara in California offered students a computerized student-aid service for a fee of $15. A follow-up study in 1984 found that, of 117 users who responded, only two actually had found aid, and it totaled a meager $900. The university promptly dropped the service.

In short, the computers are failing at their basic task: to match students with the scholarships for which they qualify. Clients get a long list of possible grants, but on follow-up, those grants don't seem to apply to them -- or, worse, they don't exist.

Some hopefuls apply to more than one computer service. But even though these services have different names, most of them get their information from the same central computer banks in New Jersey, run by Academic Guidance Services. So you may be paying twice for the same information.

CSAS expected to find varying degrees of effectiveness among computer-search organizations -- some good, some bad. Instead, Marmeduke says, "it found that not one (regardless of the size of the data base) could provide effective matching" of student to grant.

This is not to say you shouldn't seek out sources of private aid. If you're very lucky, you may find a free grant that substitutes for a college loan. But based on the record so far, the computerized scholarship services can't help you very much. Your best bet is still the traditional one: Seek advice from the college's own office of financial aid.