NOCTI Heating, Ventilation, and Air Conditioning (HVAC) Practice Test

In the evaporator, the refrigerant absorbs heat from the surrounding air and changes from a liquid to a vapor. This phase change—vaporization—is driven by the low pressure and low temperature of the refrigerant as it passes through the evaporator coil, which cools the air you’re trying to condition. Condensation happens in the condenser when the refrigerant releases heat and becomes a liquid, while subcooling occurs after condensation to cool the liquid further before it reaches the expansion device. Freezing is not the intended primary process of the evaporator, though ice can form if the coil becomes extremely cold under certain conditions. The key idea is that the evaporator’s job is to vaporize the liquid refrigerant by absorbing heat.