For more than 30 years, television has been urging Americans to buy everything under the sun and promising them the moon to go with it. Now commercial TV faces its greatest challenge yet: promoting the cause of reverse consumption for the age of Cutback Chic that is not only upon us but all over us.

It won't be easy. If Pavlov's dogs had listened to the same bell for 30 years, they would have salivated themselves into anorexia. Changing the conditioned response skillfully programmed into millions of TV viewers will require all the ingenious, vicious manipulative wizardry at Madison Avenue's command.

Are they ready for the great adventure of scaling down?

Yes, they're up for it.

The industry that sold America bigger cars, bigger homes, bigger debts and 126 different kinds of deodorant is gearing right now for the wild days of unlimited restraint that lie, like prosperity, just around the corner. Slogans for the new era are already on the old drawing board: "Why Not Settle for Second-Best?"; "Accept A Substitute" and "America, You Can't Afford It."

If the hoot-owls and jaybirds of the Carter administration get their way, it's going to be considered just short of treason to use a credit card, drive four blocks to the grocery store, or covet thy neighbor's crock-pot. Obviously this kind of guilt-think is going to require a massive realignment of the "buy-me" propaganda we see every three or four minutes on television.

Millions of dollars will be spent to persuade Americans not to spend millions of dollars. Companies will retool their strategies for the New Deprivation. The bottom line will be getting lower.

Already United Air Lines is rumored to be test-marketing a campaign keyed to the theme of "the nasty skies," or, at best, "the indifferent skies," in an effort to discourage air travel. McDonald's might actually concede, "You do not deserve a break today -- so just sit there." The phone company is experimenting with an anti-long distance campaign called "Reach out, reach out and touch your wife."

And Alcoa, the company that "can't wait for tomorrow," may soon be declaring, "Alcoa CAN wait for tomorrow, and so can you, Fatty."

Paul Masson could take the daring move of having Orson Welles say, "We will sell some of the wine before its time." Unfortunately, Welles recently renegotiated his contract to guarantee him "all the ice cream the party of the first part can eat," so those plans may have to be junked as too costly. Masson may just decide not to sell any wine at any time, except 6:30 p.m. Fridays in Philadelphia.

Since penalties may be imposed on the use of credit cards, credit card companies will be revising sales pitches. "Relax, you've got Master Charge" is to become "Tense up, we've just lowered your credit limit," informed sources say.

Then of course there's "The American Express Card -- Don't Leave Home Without It, But Don't Try to Use It, Either."

Oil companies have been advertising for some time about how we should do them a favor and cut down on using their products even though we can't survive without them.But now letters to the Shell Answer Man are reportedly being returned unopened and marked "Addressee Unknown."

And Exxon may quietly drop the promise of "Energy for a Strong America" on the grounds that it is overstatement, in favor of a more realistic "Don't leave home at all."

At the same time, the gas company has commissioned new jingles advising those why do stay home not to turn on the heat or use the oven, and the electric company will strongly suggest doing without such luxuries as the dishwasher, stereo, electric toothbrush, and light. The only certainty is that at no time will any TV commercial advise people to turn off their TV sets.

We can expect new candor in ads heretofore known chiefly for exaggeration raised to the level of art form. Several of our nation's leading toilet papers have decided to cut back from being as soft as a baby's cheeks to merely being as soft as Bo Derek's eyelashes. Products that used to ask homemakers, "Doesn't your family deserve the best?" will now urge them "Don't be so picky" and inquire rhetorically, "Who do you think you are, anyway?"

As part of the general retreat, only three or four more kinds of designer jeans will be introduced on TV in the next month. An industry moratorium will cut the number of new cat foods marketed each year in half -- to 50. Viewers can also expect to hear such revised, temperate slogans as "Ford Has A Pretty Good Idea," "Grab Some of the Gusto," "Neither Borrower nor Lender Be" and, "If You Have A Headache, Go Lie Down."

As for the opinion-makers and lawgivers of Beverly Hills and Georgetown, they are prepared to go all the way with this and prove they can tough it out with the average Joe. And Joan. For instance, many have recently discovered that drinking water comes out of taps in the kitchen and the bathroom and not only out of little green bottles from France.

The clarion call has sounded. The horn of plenty is blowing taps.