Under EPA regulations, which method can be used to pressurize an R-11 or R-123 system for non-major repairs?

The correct answer, warming the refrigerant, is appropriate for pressurizing an R-11 or R-123 system during non-major repairs because it utilizes the physical properties of the refrigerant itself. By increasing the temperature of the refrigerant, its pressure will rise according to the principles of gas laws. This method allows for safe and effective pressurization of the system without introducing foreign substances or risking damage to system components.

Warming the refrigerant is particularly advantageous because it avoids the need for any additional materials or contaminants that can arise from using other pressurization methods. It is crucial in maintaining system integrity and preventing the introduction of moisture, which could lead to further complications during repairs.

In contrast, using a compressor may not be effective or advisable in non-major repairs, as it could lead to unnecessary complications or damage. Injecting nitrogen is often reserved for specific procedures, such as leak detection, and should not be used indiscriminately in pressurizing a refrigerant system. Lastly, adding an approved refrigerant complicates the procedure unnecessarily and could disrupt the existing refrigerant balance in the system. Thus, warming the refrigerant stands out as the safest and most efficient method for this scenario.