What occurs when a vacuum pump extracts air and non-condensables from a system?

When a vacuum pump extracts air and non-condensables from a system, it effectively reduces the internal pressure within the system. This process is crucial for preparing a refrigeration or HVAC system for service, as it helps to remove moisture and other unwanted gases that can affect the system's efficiency and reliability.

By creating a vacuum, the internal pressure drops below atmospheric pressure, which is essential for preventing any further contamination or reaction of refrigerants with air and moisture. This lower pressure allows for the safe operation of the system when it is restarted, as it reduces the risk of refrigerant leaks and enhances the overall performance.

The other options do not accurately describe the outcome of using a vacuum pump. For instance, achieving a temperature below freezing is not a direct result of the vacuum process, nor does it guarantee that the pressure will rise above atmospheric level or that the refrigerant will condense more effectively solely due to the vacuum. Understanding the critical role of maintaining a low internal pressure helps technicians ensure proper system integrity and functionality after servicing.