You should flush the system:

• A. Until no more oil or debris comes out of the line
• B. Until the line is completely dry
• C. Until refrigerant is fully recovered
• D. Until the compressor stops

Answer: (A)

Flushing is done to remove oil and debris that can contaminate a refrigeration circuit after work or a component failure. The goal is to purge the system so that the passages are free of contaminants before recharging with refrigerant.

The best choice means keep flushing until no more oil or debris appears from the line. Seeing oil or debris stop being expelled indicates the internal passages are clean enough to prevent contaminating the new refrigerant and metering devices. If you stop earlier, contaminants may still be present and cause clogging or poor lubrication.

Drying the line completely isn’t the objective—some residual oil is normal and expected for lubrication and seals. Refrigerant recovery is a separate step and isn’t what determines when flushing ends, and the compressor stopping has nothing to do with the flushing process itself.