THIS WEEKEND has enough first-run openers, sneak previews and repertory films to keep you in constant air-con/ditioned comfort. In addition to openers Benji the Hunted, Devil in the Flesh, The Hanoi Hilton, Roxanne, Shadey and Tampopo, there are sneaks all over Major Metro Town of Stanley Kubrick's Vietnam movie Full Metal Jacket, the scare-flick Hell Raiser and Chris Columbus' comedy Adventures in Babysitting, all three on Friday. And Joe Dante's Innerspace, with Marty Short, will sneak Saturday. Check the ads for the numerous times and locations. There's also a $30-a-seat showing of Dragnet, starring Tom Hanks and Dan Aykroyd, to benefit the nonprofit Washington Area Lawyers for the Arts. Call 861-0055.

There are also a number of non-first-run films worth mentioning: Friday at noon, free, at the National Archives Theater, is CBS' Harvest of Shame, a 1960 study of the miseries of migrant workers. The intense, chain-smoking Edward R. Murrow, who narrated this social document, is just as commanding after all these years . . . Sidwell Cinema, which shows good repertory films for $3.50 in a comfortable theater at the Sidwell Friends School, screens a Festival of Dada and Surrealism through Sunday, featuring works by Hans Richter, Rene' Clair, Man Ray, Marcel Duchamp and others. Friday's show at 7:30 only; Saturday's at 7:30, 9:10, 10:50; Sunday's, 5:30 and 9:05 . . . Bernardo Bertolucci's eloquent The Conformist will be shown at American University's Wechsler Theater, Friday at 7:30, free. The film will be followed by a psychoanalytical lecture on Bertolucci's films . . . Helene Klowdawsky's documentary, Painted Landscapes, is about British painter Sue Coe, famous for her dark visions of New York. Friday's free showing at 8, is at the Hirshhorn Museum Auditorium . . . At the American Film Institute, Richard Lester's Petulia (Julie Cristie, George C. Scott) has perennially nudged elbows with films by Jean Renoir and Akira Kurosawa on critics' all-time-great lists since 1968. Friday at 6:30 (also 6:30 Monday). $4.50 for non-members . . .

Monday, Jean-Luc Godard's 1983 First Name Carmen (starring Murushka Detmers from Bellochio's "Devil in the Flesh") screens at 8 at the American History Museum's Carmichael Auditorium. Admission is $6.50 for non-members . . . At the same time, Martin Luther King Memorial Library will show the documentary Jesse Owens Returns to Berlin, also free . . .

Sensation-seekers, you don't have to see To Fly for the 44th time. Saturday at noon, the Maryland Science Center (601 Light Street, Baltimore) officially opens its new IMAX theater with an air show, a marching band (parading from the Inner Harbor to the Center), a 10,000-balloon release and an appearance by the Oriole Bird. The IMAX theater will begin its hourly, and daily, runs of Speed, a film that traces man's fascination with and harnessing of same. The screen, which you sit real close to, is five stories high. For those of you who haven't seen 70mm projection, it's a pristine, oversized joy for the eyes. And your eardrums will vibrate to the 7,000-watt, 38-speaker sound system. Admission to the theater only (the complex includes the theater, the Science Center and the Davis Planetarium) costs $4.50. Admission to the Science Center, theater and planetarium is $7.50 for adults, $7 for children. The theater's open every day; shows on the hour from 11 to 8.