Computational Fluid Dynamics (CFD) analysis has been used extensively in the design of automotive HVAC systems with the objective of optimize system performance and shorten the product development time. In this paper, the three dimensional Navier-Stokes code STAR-CD was used to determine the overall system pressure drop and velocity field, as well as, individual component pressure and velocity field. In addition, a better insight into the flow characteristics of the HVAC system has been obtained through the CFD analysis. Thermal performance of the HVAC module can also be achieved through the use of user supplied subroutines, which model the thermal effects of heat exchangers.In this paper, two specific systems were analyzed. The first system consisted of a simplified plentum, multiple inlet designs, blower, and evaporator core. The main focus of this analysis was placed on inlet design. The second analysis was a more complete system analysis, including an plentum, inlet, blower, and HVAC module. When available, the computational results have been compared with experimental results for validation purposes.