<p>Process parameters play a crucial role in minimizing manufacturing defects and improving the properties of fused deposition modeling (FDM) parts. While most current research focuses on factors such as print temperature and layer height, the effect of cooling fan rate remains relatively unexplored. Therefore, this study examines the influence of cooling fan rates on FDM-printed parts using both polylactic acid (PLA) and short carbon fiber-reinforced polylactic acid (SCFs/PLA). The results indicate that the impact of cooling fan rate is highly dependent on printing orientation. For horizontally printed SCFs/PLA parts, mechanical properties, shape and dimensional accuracy, and surface roughness remain largely unaffected by cooling fan rate. However, for vertically printed parts, these properties are significantly influenced. Additionally, different materials exhibit distinct responses to cooling fan rate. As the cooling fan rate increases, SCFs/PLA parts experience a notable decline in mechanical properties, whereas PLA parts show greater sensitivity in terms of shape and dimensional accuracy as well as surface quality. Crystallinity generally decreases with an increase in cooling fan rate, though the variation is minimal. This study provides a comprehensive analysis of the effects of cooling fan rate on FDM 3D printing, offering valuable insights for optimizing process parameters to achieve high-quality and high-performance printed components.</p>