When an automotive A/C compressor failure occurs, it’s best practice to flush out the system before installing the new compressor. Many times when a compressor fails it sends small metal particles throughout the A/C system. These particles can clog up passages in the system and cause problems after you’ve replaced the failed compressor. Even tiny particles can cause big problems with the system. In fact, it takes less than 1/10th of a tsp of debris to completely restrict refrigerant flow in a typical system! Flushing the system to eliminate these contaminants helps prevent damage to or seizing of the new compressor as well as the other existing parts of the system.
An A/C system flush involves running a liquid solvent through the unit with vacuum pressure to clean the inside components of the system. The A/C compressor must be lubricated at all times because it is a moving part, however, the oil is circulated throughout the entire system. That means that all the components (condenser, hoses, tubes, evaporator, drier, accumulator) have an internal coating of oil. Removing the oil (and the oil film inside these components) will eliminate all of the contamination from the AC system because the oil attracts and holds contaminants in place.
It is also best practice to remove and inspect the orifice tube (if the system is so equipped). The orifice tube inlet filter screen will always tell a story about the condition of the auto AC system. Any debris or foreign material found on the orifice tube should alert you to look for other indications of contamination . In fact, some new compressors come with these additional parts in a kit.
In summary, any time you have an AC system that’s been contaminated, you should flush it before putting it back into service. There are plenty of additional benefits to doing this: elimination of an foul odors coming from the A/C vents, and even improved fuel efficiency. Cleaning dust and debris out of your air conditioner actually helps it to function more smoothly, which in turn, helps your vehicle use gas more efficiently.