Table 2 shows the effect of 100% relative humidity continuation time, odor continuation time, and the odor intensity corresponding to the evaporator operation time. Several facts were found from this result. First, by the evaporator operation time and relative humidity of inflow air, the 100% relative humidity continuation time increases in proportion to the amount of water which can be condensed on the surface of evaporator after stopping evaporator operation. Second, the odor continuation time increases proportionally with the 100% relative humidity continuation time. Third, the odor intensity decreases inversely proportional to the odor continuation time. All things taken together, the odor production in real automobiles could appear corresponding to the condensed water on the surface of the evaporator. For example, after a driver turns off the automobile air conditioner, the condensed water on the surface of evaporator will be gradually or rapidly vaporized corresponding to the inflow air and comes inside the automobile and finally the driver will perceive the odor. The vaporized water can include hydrophilic odor compounds. When the fact is considered that if the odor continuation time is longer, the odor intensity becomes weaker, the evaporator operation time has to be short from 10 to 20 min (inflow air temperature: 25 ◦C; inflow air relative humidity: 50%; air flow amount: 200m3/h) for effective odor sampling and evaluation.