FAA AMT (Aviation Maintenance Technician) Airframe Practice Exam

The correct answer is B - Lower the temperature of the cabin air.

The evaporator in a freon cooling system is responsible for absorbing heat from the cabin air. As the refrigerant evaporates in the evaporator coil, it absorbs heat from the air passing over the coil, thus cooling the air. This cooled air is then circulated back into the cabin to provide a comfortable temperature for the occupants.

Options A, C, and D are incorrect:

A. Increase the humidity - The evaporator is not responsible for increasing the humidity in a freon cooling system. Its main function is to cool the air by absorbing heat.

C. Filter the cabin air - While some systems may have additional filters installed in the air conditioning system, the primary function of the evaporator is not to filter the cabin air.

D. Circulate the cabin air - Circulating the cabin air is the function of the fan or blower in the air conditioning system, not the evaporator. The evaporator's role is to cool the air by absorbing heat.