New Britain, Conn. — A punishing hail and rain storm beat on the windshield, as the car with license plate ''US Congress 6'' wound its way through the hills of western Connecticut.
The auto neither stopped nor slowed much as it carried Rep. Nancy L. Johnson to the corner of the state and a meeting with a handful of Young Republicans in Salisbury. After a brief stay, it was back into the storm for another hour's drive to a town meeting in Roxbury.
The frenetic pace, continuing late into a recent Saturday night, is standard for Representative Johnson, one of the few Republicans who captured a Democratic seat in 1982. She has never stopped campaigning in her majority blue-collar Democratic district.
''One of the big responsibilities of a congressman is not to get hooked on Washington,'' she said, as she pored over mail and news clippings while en route to New Millford for a town meeting.
The 50 constituents who filled the courtroom there came prepared, some with speeches, reflecting the political awareness of the New England town.
''What is happening in Central America is a relative sideshow,'' said Alan Ellis of Sherman, Conn., who added that he had grown up in Mexico, which he considered far more important to the US. He maintained that the Reagan administration is also sidetracked by Lebanon instead of focusing on Israel and the Palestinians.
The first-term congresswoman steered a moderate course as she responded to questions, usually with detailed answers that pushed the meeting to nearly two hours. She kept a careful distance from the Reagan administration, without straying too far.
In a district where education is a top priority and which is home to some of the most prestigious boarding schools in the US, she defended spending federal money for education. But she also praised the President's ''leadership'' in calling for merit pay for teachers.
As for the New Right's social-issues agenda and censuring of television shows , she offered no support. ''You cannot mandate moral behavior, particularly from Washington,'' she told the New Millford residents.
As the generally friendly meeting ended, she still had some skeptics. Christopher Charles, a general contractor from Washingon, Conn., concluded, ''She's too supportive of Ronald Reagan.''
''She strikes me as an honest woman of integrity,'' he said, but added that he wants a representative who won't be as trusting of Reagan.
Mrs. Johnson, the wife of a New Britain obstetrician and the mother of three, moved from community volunteer into state politics and then into Congress.
The alternative in the November election will be a sharp contrast with the incumbent. Democrat Arthur H. House has spent most of his career working in top foreign policy jobs in Washington and has never before run for public office. More professor than politician, he has a doctorate and worked for former Sen. Abraham Ribicoff.
His charge against the incumbent is not that she has neglected her district, but that she has neglected Washington. Not that she has spent too little time with constituents, but given too little attention to lawmaking.
The challenger, however, faces a formidable candidate in the outgoing Mrs. Johnson who, with the election still nine months away, will travel an hour through a storm to see a handful of constituents.