Automotive Service Excellence (ASE) Air Conditioner Certification Practice Exam 2025 – Your All-in-One Guide to Exam Success!

The function of the expansion valve in an A/C system is to regulate the flow of refrigerant into the evaporator. This valve is crucial for maintaining the proper pressure and temperature of the refrigerant as it enters the evaporator. Specifically, the expansion valve allows the high-pressure liquid refrigerant from the condenser to expand and convert into a low-pressure vapor. This transition is essential because it enables the refrigerant to absorb heat from the interior of the vehicle as it passes through the evaporator. By controlling the amount of refrigerant that enters the evaporator, the expansion valve ensures that the system operates efficiently and effectively, providing optimal cooling performance.

Understanding the expansion valve's role helps clarify its importance in the refrigeration cycle. It directly influences the cooling capacity of the air conditioning system by ensuring that the evaporator has just the right amount of refrigerant to facilitate heat exchange without flooding or starving.

In contrast, the other options do not accurately describe the function of the expansion valve within the A/C system.