This study examines the impact of AI course assistants on student learning experiences in online undergraduate courses at Los Angeles Pacific University. A controlled experiment involving 92 students across treatment and control groups was conducted to evaluate the effectiveness of AI assistants developed by Nectir. The treatment group had access to AI assistants, while the control group did not. The study measured grades, intrinsic motivation, self-efficacy, and students' perceptions of engagement, encouragement, and support. Results indicated that the AI course assistants significantly improved students' grades and intrinsic motivation, with moderate effect sizes observed. Self-efficacy also showed a significant positive impact, suggesting that AI course assistants can enhance students' confidence in their academic abilities. However, there were no statistically significant differences in students' feelings of engagement, encouragement, and support, potentially due to the high-touch model already in place at the university. The findings underscore the potential of AI technology to complement existing student support systems, providing continuous personalized assistance that can improve academic performance and intrinsic motivation. Further research is recommended to explore the long-term effects of AI course assistants and their interaction with other support mechanisms to optimize student outcomes and address equity gaps in online education.