Did you know? For refrigeration purposes, there are three states of matter. Solid - In a regular sealed refrigerant piping system, there should only be refrigerant existing as a liquid, vapor, or refrigerant oil. If a sealed system is compromised with contaminated moist air, and that moisture travels to the low-pressure section of the system, the corresponding drop in temperature will cause the moisture to freeze, creating ice, a "Solid," causing a blockage in the refrigerant flow, which stops heat exchange. Vapor - Refrigerant exists in a vapor or gaseous state when the pressure exerted upon the refrigerant vapor is at or below its boiling point. Liquid - Refrigerant in a sealed piping system that is above its boiling point exists in a liquid state.