A/C Flush FAQ
Question: When should the system be flushed?
Answer: We believe if the a/c system is opened for service, it's a good time to flush. A clean system minimizes the chance of a comeback. On systems that utilize an orifice tube, you can usually judge the condition by looking at the inlet side of the orifice tube screen. If a substantial amount of debris is found, flushing would be recommended. Likewise, visual inspection of the refrigerant oil may indicate it's time to flush. Question: When I flush my system, can the compressor be flushed too?
Answer: No, not with typical solvent flush methods. The compressor should be removed from the vehicle and the oil drained from it. You can pour refrigerant oil into the suction port and turn the compressor hub by hand which will pump clean oil through the compressor. Remember, compressors don't compress liquids. So, make sure you rotate the compressor hub by hand enough to ensure you don't liquid "slug" the compressor.
Question: Can the accumulator or Filter Drier be flushed?
Answer: No. Since these are filters which contain desiccant, they are considered normal replacement items.
Question: Can I flush the hoses and lines?
Answer: If you're sure the solvent that you are using will not harm rubber or nylon, then it's alright to flush the hoses. Just make sure that you don't flush trough any hoses that have mufflers built into them. And also make sure you don't attempt to flush through the compressor or expansion device.
Question: I noticed my A/C hoses have mufflers. Can those be flushed?
Answer: Though many technicians will flush through hose mufflers, it's usually not considered a good idea. As a general rule, hoses with mufflers should be replaced instead of flushed. Since the muffler is only used to reduce noise, some people opt to remove the muffler in order to salvage the hose.
Question: Can I flush through the Orifice tube or expansion valve?
Answer: No. Flushing through the orifice tube or expansion valve is too restrictive to the flow of solvent. There is one exception of course. On some Ford models the orifice tube cannot be removed without cutting the liquid line. We know of technicians who often remove the liquid line and back flush through it. In theory, back flushing the liquid line will clean the orifice tube. This is said to work in most cases; though replacing the liquid line is the preferred method. Remember, a dirty orifice tube can starve a compressor of oil.
Question: Should the evaporator be flushed?
Answer: Most would say yes, but some would argue that it's not worth the extra effort for two reasons. Flush solvents can be very difficult to remove from some evaporators. Sometimes the risk of not being able to remove the solvent outweighs the benefit of flushing that component. Secondly, some would point out that evaporators stay fairly clean because any dirt floating around the system is captured first by the receiver drier, then by the inlet screen of the expansion valve. In the case of an orifice tube system, most debris would be caught by the orifice tube screens before it could reach the evaporator. While this is mostly true, systems that use the block style expansion valves have no inlet screen, and dirt from a ruptured receiver drier could find its way into the evaporator. Also, oil likes to accumulate in low-lying areas of the evaporator. If your goal of flushing is to remove dirty oil, you'll have plenty of it in your evaporator.
(LANSDALE, PA) October 29, 2002 -The Mobile Air Conditioning Society (MACS) Worldwide has compiled recent results from a survey of its members on refrigerant usage in independent service facilities. The results will also be published in the November/December 2002 issue of MACS ACtion™ magazine. MACS asked five questions covering service of the refrigerant system and three questions addressing service equipment. The results have been collected from 109 independent service facilities and have not been independently verified by MACS.
1. In the past year, what percentage of systems you serviced (returned to customer) requiring repair used R-12 (CFC-12)? What percentage used R134a (HFC-134a)?
The survey results indicate 26% of vehicles serviced in the respondent group of 109 service shops used R-12 and 74% used R134a.
2. In the past year, what percentage of systems requiring mobile A/C repair had contaminated refrigerant in the system?
The average fleet refrigerant contamination was 12.7%. However, contamination of less than 3% was reported in 40% of the serviced fleet. Contamination levels of 10% were found in 15% of the fleet and levels over 50% were reported in 13% of the fleet being serviced. These contamination rates were based on the results of survey question #6 in which 86% of the respondents use refrigerant identifiers.
3. In the past year, what percentage of systems requiring mobile A/C repair contained hydrocarbon refrigerant?
Hydrocarbon contamination was reported in 6.4% of the survey fleet. Hydrocarbon contamination levels of less than 3% were found in 69% of the fleet. Levels of from 10 to 70% were reported in 21% of the fleet. The sale of hydrocarbon refrigerants for mobile A/C use has been identified in various regions of the country.
4. In the past year, what percentage of systems requiring mobile A/C repair had been properly retrofitted with service fittings, a label and high pressure compressor cut off switch?
The survey results indicate that only 31.6% of the systems had been properly retrofitted prior to being serviced at their facility. This is a considerably lower percentage as compared with the 61.8% of the vehicles having been properly retrofitted as reported in the MACS 2000 Field Survey Report. Only 10% of the shops in this survey indicated that every system arriving for service had the required EPA service fittings, label and high pressure cut out switch.
5. What percentage of vehicles serviced are older than 1995-model year?
MACS' survey results indicate that 49.4% of the vehicles are older than 1995-model year vehicles. Since the phase-out of CFC-12 A/C systems started in model year 1992 and was complete in model year 1995, less than one-half of the vehicles being serviced were originally built as CFC-12 systems.
6. Do you use a refrigerant identifier when performing mobile A/C repairs?
86% of the independent service facilities responding to MACS survey reported using refrigerant identifiers.
7. Do you own a diagnostic tool?
24% of the survey respondents do not own a diagnostic scan tool.
8. If you answered "Yes" to the previous question is it helpful in servicing?
68% of the survey respondents answered that the scan tool has been helpful in mobile A/C service. The current U.S. mobile A/C passenger car and light truck fleet is estimated to be 215 million vehicles. In 2001, it was estimated that the number of "on-road" HFC-134a vehicles exceed the CFC-12 vehicles. However, with current new car warranties, many of these HFC-134a systems are not currently being serviced by independent repair facilities.
Founded in 1981, the Mobile Air Conditioning Society Worldwide is the leading forum for its specialized segment of the automotive aftermarket. MACS Worldwide's goal is to fill the industry's need for comprehensive technical information, training, and communication. MACS Worldwide represents 1600 members, including service shops, installers, distributors, component suppliers, and manufacturers in the United States, Canada and countries around the world.
|
