Air Conditioning (A/C) and Heating Certification Practice Test 2025 - Free Heating and Cooling Certification Practice Questions and Study Guide

Bubbles in the sight glass indicate that the system is low on refrigerant. In an air conditioning system, the sight glass is used to visually assess the condition of the refrigerant as it flows through the system. If the sight glass shows bubbles, it means that the refrigerant in the liquid line is not at an adequate pressure or quantity to fully fill the sight glass. This condition often arises when there is insufficient refrigerant, leading to an imbalance that can result in the presence of vapor, which appears as bubbles rather than a steady stream of liquid refrigerant.

Maintaining the proper level of refrigerant is essential for the efficiency and proper functioning of the system. Low refrigerant levels can lead to inadequate cooling performance and potential damage to the compressor if the situation is not corrected. Therefore, identifying bubbles in the sight glass is a crucial step in troubleshooting and maintaining the system’s health.