Which factor is least likely to affect refrigerant recovery effectiveness?

The factor that is least likely to affect refrigerant recovery effectiveness is indeed the color of recovery equipment. The color of the equipment might have aesthetic or branding implications, but it does not influence the operational efficiency or functionality of the refrigerant recovery process.

In contrast, ambient temperature plays a significant role in recovery effectiveness, as higher temperatures can increase vapor pressure, making it easier for refrigerant to be recovered. System pressure also directly impacts the efficiency of recovery; higher pressures can mean that more refrigerant can be extracted, while lower pressures might hinder the recovery process. The type of refrigerant is crucial as well, as different refrigerants have varying properties that affect how effectively they can be recovered, including their pressure-temperature characteristics and how they behave during the recovery process.

Therefore, while the other factors directly influence how well the recovery operation functions, the color of the recovery equipment does not have any bearing on the effectiveness of refrigerant recovery.