At what temperature should evacuation of the refrigeration system not be attempted?

Evacuation of a refrigeration system should not be attempted at temperatures above 20°C (68°F) because at higher temperatures, the refrigerant within the system can exist in a vapor state rather than a liquid. This can lead to incomplete evacuation, as some of the refrigerant may remain in the gaseous state, making it more difficult to achieve the necessary vacuum levels required for system maintenance or repair.

When attempting evacuation, the goal is to remove moisture and contaminants from the system. At temperatures below 20°C, the refrigerants are more likely to condense into a liquid, facilitating a more thorough evacuation process. If the ambient temperature is too high, it can compromise the efficiency of the evacuation, increasing the risk of moisture retention and potentially leading to system damage or inefficiencies when the system is recharged with refrigerant. Therefore, the correct operational practice is to avoid attempting evacuation at or above this temperature threshold.