NATE Air Conditioning and Heat Pumps Practice Exam

What is the purpose of a Texas A/C system's expansion valve?

1. To control refrigerant flow into the evaporator

2. To increase refrigerant pressure before compression

3. To monitor system pressure levels

4. To heat the air before distribution

The correct answer is: To control refrigerant flow into the evaporator

The primary function of the expansion valve in a Texas A/C system is to control the flow of refrigerant into the evaporator coil. This component is crucial because it reduces the pressure of the refrigerant, allowing it to expand and absorb heat effectively when it enters the evaporator. By carefully modulating the amount of refrigerant that enters the evaporator, the expansion valve ensures that the system operates efficiently and provides optimal cooling. In contrast, increasing refrigerant pressure before compression is the role of the compressor itself, not the expansion valve. Monitoring system pressure levels is typically handled by gauges and sensors rather than the expansion valve. Heating the air before distribution is a function associated with heating systems or heat pumps in heating mode, not the role of an expansion valve in cooling operations.