This research focuses on studying OpenFOAM's capability of underhood thermal simulations and investigating the performance of various fan modeling techniques in comparison to other commercial software packages. An isolated fan is modeled in OpenFOAM using Moving Reference Frame (MRF) and Actuator Disk techniques. To evaluate their performances, the simulation results are compared to the experimental data which was provided by a fan testing facility and the available simulation results from Star-CCM+ and ACE+. The pressure rise is the main parameter that is used for comparisons. To further investigate OpenFOAM's capabilities, a full vehicle model using MRF technique is studied and the airflow rate across the radiator from simulation results was compared to experimental data and ACE+.