Flushing and Cleaning the A/C System Once an AC system has been contaminated or has suffered a failure, the most important part of the AC service to restore the cooling performance to the system = FLUSHING WITHOUT proper flushing procedures, seizing a new or rebuilt compressor is a real possibility. What is flushing ? Flushing is performed in order to remove all contamination (dirt) from the system. The smallest particle of contamination cause restriction and problems for a good function of the replaced compressor. It takes less than 1/10 of a teaspoon of debris (dirt) to completely restrict flow of refrigerant and oil in the typical auto AC system. Cleanliness and proper flushing procedures are very important Why / When flushing ? The AC compressor must be lubricated at all times. The AC compressor is the only moving part in the entire system and the only reason for oil in the system. The oil is being circulated throughout the system, that means that all the components (condenser, hoses, tubes, evaporator, drier, accumulator) have some coating of oil internally. If any dirt, debris or contamination happened in the system all components are affected. Removing the oil (and oil film inside the components) will eliminate all of the contamination from the AC system. It’s the oil that attracts and holds contaminants within the system. Remove the old oil = remove the contamination.
The AC system must be flushed whenever the AC compressor is being replaced/removed or whenever there is indication of contamination within the system. Make it a habit 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 cause you to look for other indications of contamination. (see picture)