Minimizing the power consumption of an automotive HVAC system is one of the main focuses of the automotive industry in the current day, as a reduction HVAC in power consumption can improve vehicle efficiency and provide customers with a higher quality product. During defogging operations in cold weather, the HVAC is programmed to maintain a condensation-free windshield but the question of “is the defogging operation as efficient as possible?” remains. This research develops a 1-dimensional mathematical methodology to predict the thermodynamics and psychometrics of steady-state heat exchange through the front windshield. This methodology is implemented in Siemens AmeSim software and applied for multiple possible environmental scenarios to develop a predictive simulation tool that can be used by Stellantis engineers for the purpose of improving energy efficiency of the HVAC system during vehicle development and improve the defogging strategy.