ACS evaporator consisting of aluminum absorbs heat from the cabin air and removes its moisture, hence the odor could be caused by the matter accumulated when indoor and outdoor air passes through the evaporator’s fins. These matters could be used as nutrition for microorganisms [6,7] and converted into odor compounds by decomposition. Therefore, it is difficult to identify odor-active compounds emitted from ACS only with simple instrumental approaches. In odor research, it is well established that the odor thresholds of volatile compounds can differ by many orders of magnitude (e.g., parts per trillion up to odorless compounds) [8,9]. The relationship between concentration and odor intensity may also vary considerably between compounds. Because of the large variation in these two properties, the response of a chemical gas chromatography detector (e.g., a flame ionization detector or a mass spectrometer) is not representative of odor activity. For example, the most abundant compounds in a chromatogram may not be the most important odorant [10]. Consequently, the impact of a compound on the odor of a sample must be evaluated using human assessors [11]. A valuable tool for identifying character-impact odorants is gas chromatography–olfactometry (GC–O), wherehuman“sniffers” are used to detect and evaluate volatile compounds as they elute from a GC column [8].