Air Conditioning Repair Certification (ETI) Practice Exam 2025 - Free Air Conditioning Repair Practice Questions and Study Guide.

Introducing refrigerant as a liquid using a throttle valve is the optimal method for adding refrigerant to the low side of an operating system. This method ensures that the refrigerant enters the system in a controlled manner, allowing for efficient absorption of heat as it evaporates in the evaporator coil. By introducing the refrigerant as a liquid, the system can maintain proper pressure levels and experience immediate changes in state when it reaches the evaporator, where it absorbs heat from the surrounding air.

Using a throttle valve allows for the regulation of the flow rate and pressure, ensuring that the refrigerant is metered correctly and prevents flooding of the evaporator, which can reduce efficiency and cause damage to the compressor. The controlled introduction also helps to prevent issues such as slugging, where liquid refrigerant enters the compressor, which can harm the equipment.

In contrast, introducing refrigerant as a vapor wouldn’t provide the immediate cooling effect needed within the evaporator, as the vapor would need to undergo a phase change before it can absorb heat effectively. High-pressure gas from a cylinder might not be appropriate for the low side and could pose risks if not managed properly. Allowing refrigerant to self-evaporate is not practical in this context, as it will not provide