If the label identifying the refrigerant is missing, which method is used to identify the type of refrigerant?

The correct choice for identifying the type of refrigerant when the label is missing is the Pressure-Temperature Method. This method involves measuring the pressure of the refrigerant in the system and comparing it to known pressure-temperature relationships for different refrigerants at specific temperatures. Every refrigerant has a unique set of pressure-temperature characteristics, which helps technicians accurately identify which refrigerant is present in the system.

This method is particularly useful because it relies on the physical properties of the refrigerant, which can be determined without having to open the system or introduce any substances that may contaminate it. The Pressure-Temperature Method is essential for ensuring that the correct service procedures are applied according to the specific refrigerant in use, which is critical for both safety and system efficiency.

In contrast, methods like the Color Code Method or Concentration Test may not be reliable, especially if the refrigerant is not commonly recognized or if it has been mixed with others. The Evacuating System Method is focused on preparing the system for service and does not assist in identifying the refrigerant. Therefore, the Pressure-Temperature Method stands out as a systematic and accurate approach for refrigerant identification when the label is not available.