When recovering refrigerant, what is a critical factor to monitor during the process?

Monitoring the pressure in the recovery machine is crucial during the refrigerant recovery process because it gives insight into the system's conditions and the efficiency of the recovery operation. The pressure readings help determine if the recovery is proceeding correctly; if the pressure is too high, it may indicate a problem that could hinder recovery, such as a blockage in the system or overfilling of the recovery machine. Maintaining appropriate pressure levels ensures that the refrigerant is being efficiently extracted from the system, and avoiding excessive pressures is essential for safety and proper operation of recovery equipment.

While other factors, such as the ambient temperature, can influence the overall efficiency of refrigerant recovery by affecting the gas's density, they are not as critical to monitor directly during the actual recovery process compared to pressure. Oil levels in the compressor and the color of the refrigerant do not provide necessary real-time data for effectively managing the recovery operation. Thus, focusing on the pressure in the recovery machine ensures both the effectiveness and safety of the refrigerant recovery procedure.