Which of the following statements about an evaporator is NOT true?

The statement that an evaporator is not affected by dirt or frost build-up is not true. In reality, evaporators can be adversely affected by dirt and frost accumulation. Dirt can block the airflow over the coils, which diminishes the efficiency of heat transfer and can cause the system to work harder, potentially leading to failure or increased energy costs. Similarly, frost build-up, particularly when the evaporator operates in low-temperature conditions, can also impede airflow and reduce the evaporator's ability to effectively absorb heat. Regular maintenance, including cleaning and checking for frost, is essential to ensure optimal performance of the evaporator.

The other statements accurately reflect the functions and limitations of an evaporator: it indeed removes heat from the air, it de-humidifies the air by cooling it below its dew point, and it may require defrosting in low-temperature conditions to maintain efficiency.