ESCO Air Conditioning Practice Exam 2025 – Complete Study Resource

In an air conditioning system, a sight glass is typically located in the liquid line before the metering device. This placement is critical because it allows technicians to visually inspect the refrigerant level and condition within the system. The sight glass provides insights into whether the refrigerant is liquid or vapor, which is essential for diagnosing system performance and ensuring the proper functioning of components.

Having the sight glass positioned before the metering device means that any issues related to liquid refrigerant flow can be detected early on. Observing the liquid in the sight glass can help identify whether the system is adequately charged, which is crucial for efficient operation and to prevent potential damage to the system.

In contrast, placing a sight glass in other locations, such as before the compressor in the discharge line or in the suction line before the evaporator, would not provide the same level of essential information about liquid refrigerant levels. Additionally, situating it near the oil separator in the discharge line would not serve the purpose of monitoring the liquid refrigerant needed for optimal system performance.