Harrison Ford is fidgeting.

The screen's coolest cucumber - and here he is pulling a paper napkin apart, and squeezing it back together running his index finger along the rim of a saucer rotating a coffee cup, left to right, right to left and back before starting the whole process over again. Paper, saucer, cup. Paper, saucer cup. He's coughing. He's ahem-ing. He's clearing his nose and searching for a cigarette. The guy can't seem to sit still.

This, understand, is the same Harrison Ford who can go eyeball to eyeball with danger and still be staring when danger blinks. On film, he has struck back at empires and given adventure a middle name. Off camera, the thing that tends to unravel him is having to sit back and talk about himself.

But the talking comes with the territory, so he sits and he talks, rocking a little, fussing a little, rubbing his palms and sharpening his wit. He clears his throat and throws out an explanation. "The most interesting thing about me is the work I do," he says crisply. His voice is resonant, his eyes straight ahead. 'I don't particularly like to talk. I'm not a big talker - I mean, a yakker." He's tired of the quotes about himself saying he hates to do this kind of stuff. He's tired of yakking about carpentry. He's tired of explaining his three-year hiatus from the movies between "Zabriskie Point" and "American Graffiti." And he's tired of, well, let him tell you: "Everytime I go through the process, the Han Solo file thickens with one more quote about Han Solo." (OK, so no quotes about Han Solo today, though, of course, it's not Han Solo that's gotten to him, just the same old questions.) His gaze steals around the room. His tone fills With self- mockery like a blowfish inhaling. "Tough. Too bad, old boy." That done, it's straight ahead again. "But I recognize the value. I'm here to sell a movie."

The movie is called "Witness," and this Ford-model sales pitch is coming from a suite at the Hotel Bel-Air. Its living room is enormous. The carpenter - oops - in the actor is impressed with the ceiling's woodwork, the critic in him less so by the painted sky that woodwork surrounds. Baroque isn't Harrison Ford's style. His jacket, English tweed, neatly tapers around his frame; his striped shirt is western-cut; his jeans lean more toward practicality than fashion. It doesn't take long to realize the man wearing them leans the same way, too.

At 42, he'd rather stay home than run to a party, but that most likely applied at 30 as well. He'd probably rather go to the dentist than a film premiere. "Entertainment Tonight"? Forget it. Mention the word "celebrity" and he looks as if he's just sniffed a skunk. "You're not just a ce-leb-ri-ty because you're in movies ," he cautions. You have to be in People magazine to be a celebrity." He has been though. "Only accidentally," he smirks. Now for the point: "I'm not a celebrity," he says. "I'm an actor."

An actor who blasted from obscurity in a spaceship; and then cinched his star status with a leather jacket and fedora hat. Han Solo - sorry - and Indiana Jones may have made him rich and famous, but he was an actor before they came inio his life and he'll still be one long after they leave it. Two swashbuckling film roles in five Cultural Events, as he calls them, have given him a screen presence larger than life and harder to get around than a shadow. But Ford's a realist. He knows that the stuff comes and goes. As important to him are the endless second leads on episodic television and a body of features including "American Graffiti," "The Conversation" "The Frisco Kid," "Hanover Street," "Blade Runner." They, along with those five Cultural Events, helped give him a craft.

Ask him about typecasting and he points to those roles, the diversity of those roles matching the question he's come to anticipate with a few questions of his own. "What do you mean? They got the money to make these other movies. So I must not be typecast. I must be OK, right? What it always refers back to is those dollar events" - those Culture Events - "Star Wars," "The Empire Strikes Back" "Return of the Jedi" "Raiders of the Lost Ark," "Indiana Jones and the Temple of Doom." You almost expect him to pull out his whip and snap the observation into oblivion forever. "Hey," he says grinning, "I always broke the mold."

"Witness," directed by Australian Peter Weir and co-starring "Rueben, Reuben's" Kelly McGillis, cracks that mold into new bits and pieces. His toughness is grittier, his mien more urbane, his character more contemporary and romantic than the heroes he tends to be associated with. He is the fulcrum to a film that balances the harmony of the peaceful and austere Amish of rural Pennsylvania with the dischord of modern-day urban violence and corruption in Philadelphia and its police department. Ford plays John Book, a Philadelphia police detective called in to investigate a drug-related murder, witnessed from a men's room stall by an Amish boy, McGillis' 8-year-old son. As Ford begins to unravel the case, he flees the city, finding refuge with the widowed McGillis and her family. There, as "Witness" blends its high-revving detective yarn into a textured and unconventional love story, he's confronted by both a clash of conscience and a clash of cultures. "The polar opposite," says Ford, "of 'An Officer and a Gentleman.'"

"The material," he says, "represented a unique opportunity, I had not seen this movie before. Eighty-five percent of the scripts I read I know where they came from. It's a second-generation effect. This was more or less a literate script for adults. I saw a movie when I read it. It felt like a movie to me, and many things do not. On paper, 'Witness' looked real. More than that, it had something to say.

"Unlike many films that get made these days, it's got a moral context," Ford stresses, "a moral point of view. It derives power and impulse from that and it derives also emotional value that the audience can experience along with the characters. There's an emotional relationship to goodness here, not just a visceral relationship to seeing something violent and horrible on screen."

Once Ford attached himself to the Paramount project, the film was a go. The next step was to find a director. Ford's deal gave him approval, and the man he wanted was Weir, but the Australian who'd most recently helmed "The Year of Living Dangerously" had already signed to direct the adaptation of Paul Theroux's best-selling novel "The Mosquito Coast." When that failed to come together, Paramount sent him "Witness," says Ford, "He responded to it almost immediately." After meeting with Ford, Weir committed.

Before shooting began, while other members of the cast were learning facts about the Amish, Ford pounded the beat with the Philadelphia police department's homicide squad. "I went on a couple of things with them," he recalls, "but the action wasn't as informing - although it was informing, it was interesting - as a lot of the tension and the manifestations of tension that I saw. The way people behave themselves in real tense situations such as kicking down the door of a fugitive murderer's hideout. In those situations I saw behavior in which I felt more free to create behavior because of the experience I had. And, as well as those things which make good war stories, I learned as much from sitting around and having a cup of coffee. These guys mostly think. They spend most of their time connecting and reconnecting various complicated relationships, following up on mundane details, deciding what's important and what's not, using an incredible variety of means."

Not unlike what he has to do as an actor. "There are days," he admits, "when it's harder to run than it is to think; and days when it's harder to think than it is to run." Either way, he's faced with choices. "Even if you're going to run, whether to turn around and look behind you or to keep your eyes straight ahead. I do whatever physical action I can because in the midst of aIl this physical action there is a lot of opportunity for characterization. "These," he says, returning to the cops he hung around with, "are people under pressure, and the attitude in your head and the wildness in your eyes can make a deep impression at just the right moment. It's all part of the same game."

Ford began learning the game in college in Wisconsin. He was rooting around in English and philosophy, not the most practical of subjects, even in the pre-yuppie dawn of the early 60's, just going along, he remembers, "with no plan whatsoever until I took a drama class trying to get my grade average up and meet some girls." His average improved, he met his first wife and, at the end of his senior year (he didn't graduate), headed for Hollywood. Columbia Pictures signed him to a contract.

"I was doing a play in Laguna Beach and someone there kindly offered to set me up for an appointment with a casting director," he recalls. "And I walked in and they said how tall are you, what do you weigh, do you speak any foreign languages, can you ride a horse? OK, kid, thanks a lot, if we find anything we'll let you know." Fate, however, intervened, pressing hard on his bladder. When he left the office, he made a detour to the men's room. When he walked back out to the elevator, the casting director's assistant was calling him back. "And I knew," says Ford, "I always knew right from the beginning that if I had gone down the elevator instead of going to take a pee it wouldn't have been worth chasing me down the street."

Ford played a bellboy in his first Columbia picture, 1966's "Dead Heat on a Merry-Go-Round," and a studio executive told him, "You ain't got it, kid," the "it" being star quality. Ford laughs at the story now, but protested at the time, eventually leaving Columbia for a similar contract with Universal. Again, small parts followed. "But I don't think I was fit for anything else then, actually," he says. "I needed a lot more experience before I was worthy of better parts. But you have to work over your head, and you still have to look to work over your head a little bit."

When those opportunities didn't come, Ford decided to take a hiatus after "Zabriskie Point" in 1969. "I was sort of becoming known for kind of second or third guest star parts on television and sort of wearing out my face and wasn't learning anything very much and wasn't gaining, wasn't building the kind of reputation I wnated because I wasn't doing the kind of work that I wanted," he explains. "So rather than have to take every acting part that came along in order to make money for food, I became a" - here we go again - "carpenter. But I never gave up the ambition to be an actor. I was always more or less available for something really good."

Which came in the form of George Lucas' "American Graffiti." Four years later, Lucas' "Star Wars" took off, and Ford, and his career, took off with it. His marriage, however, was left behind. He divorced his first wife in 1979. They remain amicable, he says, and he sees his two teenage sons as often as he can. In 1981, he married Melissa Mathison, the screenwriter of "The Black stallion" and "E.T."

Next year, he'll be off to wherever with Lucas and Steven Spielberg for the third installment of the "Raiders" saga. Announcements will be forthcoming soon, he promises. "There's little else I can tell you about it." But he can hint that it won't carry quite the same tone as "Indiana Jones and the Temple of Doom." More somber and violent than its megabucks predecessor, that film was heavily criticized for its excesses. Ford refuses to slip in specifics, but you can't escape the feeling that he was less than thrilled with what went up on the screen. "This sort of falls into that private area of how you deal with the people that you work with, and I don't want to go over any of that," he says. "But if I had agreed totally with everything that they had done, we could talk about it, but I don't, and so I can't. Still," he adds, "You hate to see (a Spielberg) miss an opportunity to give you pleasure."

Ford picks up the napkin that he's been fidgeting with for the last hour. It's now tightly rolled into a ball, and he arcs it in the direction of a wastebasket on the far side of the room. He misses, but just barely. It's one of the few opportunities he's missed in a long time.