After recovering all liquid refrigerant during a system overhaul, what is the next step?

After recovering all liquid refrigerant during a system overhaul, the next step is to recover all vapor from the system. This process is crucial to ensure that the system is completely devoid of refrigerant before any maintenance or repair work is performed. Recovering both the liquid and vapor prevents contamination and ensures the safety of technicians during the overhaul.

The recovery of vapor helps in minimizing the pressure in the system, allowing for proper maintenance and inspection without the risk of refrigerant leaks or exposure. Additionally, it ensures the integrity of the system by removing any remaining refrigerant, which may contain contaminants that could affect the performance and longevity of the equipment.

In the context of the other options, replacing filters, adding more refrigerant, or cleaning evaporator coils should occur only after ensuring the system is completely evacuated of refrigerants, both liquid and vapor. These activities are critical maintenance tasks but would be premature without first ensuring the system is free of refrigerant.