Corporate political action committees -- groups that openly collect campaign money within a company from executives and other white-collar employes to give to politicians -- have become the fastest growing phenomenon on the political money scene.

Just over two years ago ago, when company fund-raising was in a legal gray area, there was 139 open corporate PACs. Political Action Committees, or PACs, according to Federal Election Commission officials.

Today, with the double blessing of the FEC in 1975 and the 1976 federal election law, there are some 538 and the number is growing daily.

"It took us a long time to catch up with the unions," was the way one Washington-based company put it recently.

Since most companies didn't start their fund-raising until late 1976, it's difficult to determine just how much new money these corporate groups will raise and distribute this election year.

An FEC report released earlier this month shows that, for 1977, the corporate PACs raised $3.6 million and labor organization committees raised $7.2 million. Trade association and professional membership organizations, such as for doctors (which often parallel corporate interests), topped the field with $8.1 million.

Thus, despite the fears raised by some Democratic legislators and selfstyled reform groups, such as Common Cause, the corporate groups still have a way to go before they take over the political financing.

Professional fund-raising, however, see the corporate area as the most fertile field or campaign money to develop in recent times.

Although many companies are for the first time starting up gorups, some major corporations are just bringing their longtime operations out of the closet.

Take the big three auto makers.

For years, Chrysler, General Motors and Ford maintained more or less informal campaign fund-raising programs -- depending on how they viewed the legality of such operations.

Federal law, of course, forbids a corporation from using its own funds as political contributions. The recent law changes and FEC rulings, however, permit companies to pay for inhouse soliciations and maintain committees to disburse the money.

In the past top executives often banded together at election time, put their checks in a pool and delivered them in one envelope to a candidate or political party.

Thus a 1972 list of contributors to theNixon reelection campaign, maintained by the former president's secretary RoseMary Woods, carries a notation of $133,844 from "employes of Chrysler" and $851,012 from employees of GM Corp."

In 1976, an open Chrysler Nonpartisan Political Support committee was established and filed with the FEC. Instead of a once-a-year letter from the Chrysler board chairman to executives, there is a regular solicitation, collection of donations and distribution of contributions to members of congress selected by a board of trustees.

The candidate recipients come from a list supplied by Chrysler's Washington office which, according to a company official, notes "plant city congressmen," as well as "members of committees on which we have some involvement and congressmen with whom we have dealings."

Chrysler even publishes an annual list of what it raised and to whom the money went.

"It showed we had 80 percent winners," the official said, "and that's the first time executives knew what happened to their money."

Thus, for example, last year the largest single Chrysler donation was $1,000 to Sen. Donald W. Riegle Jr. (D-Mich) who was elected in 1976 but needed money to pay off his deficit.

Riegle also completely changed his position on the need for airbags as a car safety device. He went from being the first senator to favor airbags to declaring himself against them.

The airbag change, though it came around the time of the Chrysler contribution, was not a factor in the company's giving the money, according to a Chrysler official. Riegel did, however, hold a joint meeting in his office with Chrysler executives and Joan Claybrook, head of the National Highway Traffic Safety Administration, debating the issue.

The new open Ford and GM PACs are younger than Chrysler's and have yet to operate for a year.

GM, for example, reported last month that it collected $57,296 in 1977 from its first in-house solicitation, and failed to make any contributions. Overall GM expects some $90,000 to be raised for this year's elections.

Under the GM system, contributions go to a Detroit bank so employes don't show their bosses whether they have contributed.

The money can be earmarked for a specific candidate or party, or it can go into a company pool of funds.

Distribution is governed by a GM selection committee which, as with Chrysler, looks at congressmen with facilities," according to a GM spokesman.

"We also have specific guidelines," he said, such as "consideration of votes on issues of importance to the corporation and leadership in Congress and on committees in support of private enterprise."

To get its PAC rolling, GM sent a team out with a slide show to push the PAC and talked to executives and administrative employes at all plant sites, "but not blue-collar workers," the spokesman said.

The latter group, who belong to the United Auto Workers union, already participate for the most part in UAW's campaign fund operation, which has been making substantial political contributions for years.

The Ford PAC got off to such a slow start last year that the company hired consultants to perk it up.

With the help of a documentary movie, which was shown in Ford plants around the country, they did just that.

Jay Smith, formerly with House Minority Leader John J. Rhodes (R-Ariz.), was partner in the consultant firm that worked for Ford. The film, according to Smith, was "dominated by issues that affect the auto industry . . . auto emissions, for example, with interviews with friends and foes of the company."

When the employes saw "how the the auto industry was perceived." according to Smith, many were more than eager to contribute.

A Ford Washington official said recently that the PAC has revived. "You get a double play out of the contribution giving through the PAC," he said. "The employes give and Ford looks good."

Another industry giant is testing a legal campaign fund operation --American Telephone & Telegraph.

At a time when AT&T affiliated companies in Texas and North Carolina are being investigated for previously underclosed aileged campaign fund operations, the parent concern and other affiliates are registering PACs.

Late last year, the American Telephone Political Action Committee filed with the FEC and listed as associated PACs, those Ohio Bell. Indiana Bell, Pacific Northwest Bell and Western Electric.

The corporate movement is just beginning, but business organiztions such as the Public Affairs Council are regularly holding seminars for company officials designed to aid them in starting new PACs.

Common Cause bemoans the growth, noting that corporate PACs are special interest groups "channeling contributions to incumbents."

One Ford executive responded by saying the PASs allow employes to act as "corporate citizens."