Final answer:
If the sight glass was blue or green, this typically indicates that there is moisture present in the system (option D), which can lead to issues such as freezing and corrosion, and must be addressed promptly.
Step-by-step explanation:
If the sight glass was blue or green, it would generally indicate the presence of moisture in the system. Sight glasses are often equipped with a moisture indicator that changes color based on the presence of moisture within the refrigerant. When the moisture indicator shows a blue or green color, it is often an indication that a desiccant within the system has become saturated and there is moisture present, which is option D) Moisture present.
It's important to note that moisture levels in refrigeration or air conditioning systems can cause a number of problems and incumbent damages, such as freezing and corrosion, which could lead to reduced efficiency or system failure. Therefore, resolving issues of moisture promptly is crucial for the health and efficiency of such systems.