What main substance should be avoided in refrigerant oil?

Moisture is a critical substance that must be avoided in refrigerant oil due to its detrimental effects on the refrigeration system. When moisture is present, it can lead to the formation of acid when it reacts with the refrigerant and oil, which can cause corrosion and damage to components such as compressors and evaporators. Additionally, moisture can lead to rust and the breakdown of the oil, compromising its lubricating properties and ultimately affecting the efficiency and longevity of the system. Therefore, keeping moisture out of refrigerant oil is essential for maintaining the integrity of the refrigeration system.

While other substances like acid, contaminants, and excess refrigerant can also negatively impact the system, moisture is particularly hazardous as it can lead to multiple cascading issues that compromise the performance and reliability of the refrigeration cycle.