Complex sentence: Hillin then joined Team Ireland late in the 1991 season, and then for a partial season in 1992; the team closed late in 1992, Hillin moved to Donlavey Racing, running the full 1993 season for the team.
Split into simpler sentences: Hillin then joined Team Ireland late in the 1991 season, and then for a partial season in 1992. When the team closed late in 1992, Hillin moved to Donlavey Racing, running the full 1993 season for the team.