Defroster performance is significant issue because it directly relates to safety issue during vehicle driving. There were many trials in both industrial and fundamental applicable investigations to prevent condensation by air blow with controlling heating, ventilation, and air conditioning (HVAC) systems such as increasing flow velocity, controlling flow temperature, and changing flow direction. However, these kinds of solution are limited since every vehicle has a different inside volume needing a different fluid conditions to minimize discomfort such as air blow direction, noise, and etc. In this research, we designed triangular shape vortex generator (VG) to enhance defroster performance possibly applicable to any vehicle disregarding inside volume. Tip vortex is generated when fluid from defroster flows along the VG which is controlled by size, angle of attack, and aspect ratio. Vortex improves mixing of wet air near the windshield and dry air far from windshield. Flow velocity from the defroster was measured by using particle image velocimetry (PIV) method. We chose the VG size as boundary layer thickness of the flow to maximize vortex strength. In addition, we compared VG arrangement such as angle of attack, co-rotating case, and counter-rotating case which can increase air mixing. Defroster performance was evaluated by both evaporation time and wake characteristics of vortex at room temperature. We expect optimized VG can increase more defogging effect for commercial vehicles by further study.