What are UK A-levels worth in the USA?
The short answer is no, you cannot use A-levels to establish equivalency to a junior college degree.

A junior college degree, or having junior status at a four-year university, is equivalent to two full years of study at the college level (typically about twenty classes). Three A-level courses, if they're treated as the equivalent of AP courses, would likely equate to less than two semesters of study.