Harrison Ford is on the line in a much more ambitious and risky role than the action parts that brought him fame and fortune. In "The Mosquito Coast," which opens Nov. 26, he plays an honestly motivated but abrasive, increasingly crazed and obsessed egomaniac.

The curse that Ford is probably doomed to endure is being thought of mostly for his lightweight action stints as Han Solo and Indiana Jones. The blessing is that parts in the "Star Wars" and "Indiana Jones" movies made him financially independent and a hot prospect for other projects.

"It's always been my ambition to be a --quote-- serious actor," Ford says. He proved his potential as the tough detective in "Witness," which won him an Oscar nomination. But the part, while emotionally complex, was still a heroic man of action. As the self-destructive Allie Fox in "The Mosquito Coast," based on Paul Theroux's novel, he's striving for yet another dimension.

"I feel I've taken advantage of whatever opportunities I've had," says the star, whose long list of credits during more than 20 years of acting include roles of various sizes in "Luv," "Getting Straight," "American Graffiti," and the "Conversation." His television work includes stints on "Ironside," "Gunsmoke" and "The Virginian," as well as the TV film "The Trial of Lieutenant Calley."

The 44 year-old actor, who grew up in Chicago, has been in several of the most financially successful films of all time. He expects to do another "Indiana Jones" movie next year depending on what he thinks about the script being prepared.

But he makes it clear that he's after more, and if you can believe him, instead of being offended when unrecognized on a street, he takes that as a compliment to his ability to be a character actor. "Some days I get stopped and recognized, some days I don't," he says. "I can pass unrecognized in most places. I don't think people know who Harrison Ford is. They're looking for one of the characters I play. I've always considered myself a character actor."

He's excited about his work in "The Mosquito Coast." Allie Fox is a man who worries about the world going to pieces, and browbeats his family into taking a dangerous trip into the jungle, where he believes they can survive in a new life.

"Both Peter Weir (the director of "The Mosquito Coast" and "Witness") and I thought we shouldn't be slavish to the book," Ford notes. "We needed a different Allie Fox. In the book Fox crazy from the beginning. If audiences thought that he were crazy, they'd give up on him."

He believes the Fox role is the best he's read since his part in "Witness" and thinks the movie has a lot to say about family relationships.

"It's mostly about love," the actor notes. "Fox is a love junkie of one kind or another. He requires respect and admiration from his family and everyone he meets and he bullies his family into going along with everything. He carries the seeds of destruction within him."

It wasn't only the role that excited him when he read the screenplay by Paul Schrader. After "Witness" he was eager to work again with Weir.

Ford divides his time between Los Angeles and his Wyoming ranch. He is married to screenwriter Melissa Mathison, who has scripted such movies as "E.T.," "The Black Stallion," and "Escape Artist." He has two sons, from a previous marriage, Benjamin, 20, and Willard, 17, both university students.

Questions about his relationship to his sons, in comparison to the relationship Allie Fox has with his family, prompts him to lower the boom.

"I wouldn't think of discussing my relationship with my sons in a newspaper," he says firmly. But he adds that he tries to set an example for them. "That's the only way to teach-- by example."

He's interested in conservation --his ranch is part of a wildlife preserve-- but doesn't believe he should sound off about his civic or charitable efforts.

Ford, a stickler for accuracy, points out that studio biographical material erroneously lists him as having been in the movie "Zabriskie Point," noting that "my scenes were cut out."

Nor does he let stand an implication that he was so discouraged at one time that he quit acting to become a carpenter.

"I never gave up wanting to be an actor. I became a carpenter so I'd have another way of earning a living and have some control in my life. But I don't regret having had a long apprenticeship.

"I always knew it was going to take time to get regular work, and that's what I was ambitious for-- regular work."

Now he can work as regularly as he likes.