Air is a mixture of pure substances consist of several gases including water vapour. The air cooling and dehumidification process is one to cool the air (sensible) and at the same time remove the moisture out of the air (latent). In general, the air cooling and dehumidification process is implemented as the air passes over cooling coils in which the lower temperature refrigerant or chilled water flows through. The air cooling and dehumidification process is widely used in air conditioning (AC) application. It is an important process for AC proper operation. Unfortunately, some publications, such as text books, posted class notes, and web presentation, do not describe the process properly. Many college seniors and engineers may not understand the process correctly. In the paper, the author points out the confusion in the publications. The paper analyzes the air cooling and dehumidification process thoroughly by using graphical psychrometry, equation, and example illustration. It points out that the cooling and dehumidification process is largely affected by air bypass factor (BF). The relationship of the key factors involved in the air cooling and dehumidification process is presented, such as, BF, apparatus dew point (ADP), sensible heat factor (SHF), room sensible heat factor (RSHF), and grand sensible heat factor (GSHF). The cooling coil load which is one of the important variables in AC application can be determined graphically on Psychrometric chart by the relationship of the key factors. The paper is a comprehensive presentation for analysis of the air cooling and dehumidification process through cooling coils. It is greatly meaningful in academic education and engineering practice.