What characteristic of R-407C could impact system performance?

The tendency of R-407C to fractionate into its individual components is a significant characteristic that can impact system performance. Fractionation occurs when the mixture of refrigerants separates into its constituent parts during the phase change processes, particularly under variations in pressure and temperature. When this happens, the system may not perform efficiently and can lead to inconsistent cooling performance.

As the components of R-407C separate, the properties of the remaining refrigerant mixture can change, potentially affecting the overall efficiency of the system. For instance, if one component evaporates more quickly than others, it could lead to an uneven distribution of refrigerant in the system, which could cause issues like inadequate cooling or increased strain on the compressor.

In contrast, the other options provided may describe characteristics that are generally favorable. A lower pressure drop across the evaporator, a higher energy efficiency ratio, and higher thermal conductivity are all attributes that would typically enhance system performance rather than detract from it. Therefore, the fractionation tendency of R-407C stands out as a risk factor for maintaining stable and effective operation in a refrigerant system.