What is the primary function of an orifice tube in an A/C system?

The primary function of an orifice tube in an A/C system is to regulate the flow of refrigerant into the evaporator. The orifice tube serves as a metering device that allows a measured amount of refrigerant to enter the evaporator, where it absorbs heat and cools the cabin air. This controlled flow is crucial because it ensures that the refrigerant can evaporate completely and efficiently, optimizing the cooling process.

By maintaining the correct flow rate, the orifice tube helps to operate the system efficiently and supports the A/C compressor in maintaining the desired temperature within the vehicle. The other options do not accurately describe the role of the orifice tube; for instance, it does not measure refrigerant temperature, act solely as a filter, or control refrigerant pressure directly. Its primary role is strictly related to the regulation of refrigerant flow, which is essential for effective air conditioning performance.