1、AutomotiveAir-ConditioningRefrigerantService GuideSecond EditionPhilip G. GottCopyright 1996 Society of Automotive Engineers, Inc.ISBN 978-0-7680-6847-4All rights reserved. Printed in the United States of America.Permission to photocopy for internal or personal use, or the internal or personal use o
2、f specific clients, is granted by SAE for libraries and other users registered with the Copyright Clearance Center (CCC), provided that the base fee of $.50 per page is paid directly to CCC, 222 Rosewood Dr., Danvers, MA 01923. Special requests should be addressed to the SAE Publications Group. SAE
3、Order No. R-141AAcknowledgementThanks to Angelo Patti, Chrysler Corporation; Richard Ligeski, Ford Motor Company;John Elias, General Motors Service Technology Group; and Ward Atkinson, Sun Test Engineeringfor their help with this second edition.Table of Contents1. Why Use This Service Guide? 11.1 Pu
4、rpose 11.2 The Clean Air Act, You, and Your Satisfied Customers 11.3 The Environmental Impact of Some Refrigerants 21.4 Industry Efforts to Solve the Problem 31.5 Legal Requirements 51.6 Proper Procedures and the Right Equipment 52. General Safety and Service Precautions 72.1 Safety 72.2 Cleanliness
5、 82.3 Check for Leaks First 92.3.1 Background2.3.2 Leak Detection Equipment 102.3.3 Proper Use of Leak Detection Equipment(see SAE Standard J1628): 102.4 Filling 113. Refrigerant and System Properties 133.1 Cooling Characteristics3.2 Lubricants 133.3 Contaminants 143.3.1 “Naturally Occurring“ Contam
6、inants 143.3.2 Intentionally Introduced Contaminants 153.3.3 Coping With Contaminants 153.4 Why Prevent Mixing of Different Types ofRefrigerants in Service Equipment? 154. Equipment for the Extraction-only of Refrigerantand Equipment for the Recycling of Refrigerant 174.1 Whats the Difference? 174.2
7、 Using Extraction Equipment 184.3 Using Recycling Equipment 194.4 Recycling versus Reclaiming5. Service Procedure for the Containmentof Automotive Air-Conditioning Refrigerants 215.1 Purpose 215.2 Refrigerant Recovery Procedure 215.3 Flushing 225.4 Recharge/Refilling 235.5 Use of a Manifold Gauge Se
8、t 235.6 Checking Refrigerant for Excess Air 45.7 Containers for the Storage of Recycled Refrigerant 255.8 Transfer of Refrigerant 255.9 Disposal of Empty or Near-Empty Disposable Containers 266. Retrofitting CFC-12 (R-12) Mobile Air ConditioningSystems to HFC-134a (R-134a) 276.1 Purpose: 276.2 Appli
9、cability 76.3 Retrofit Procedure 276.3.1 Inspection 76.3.2 Check for System Leaks or Other Problems 28AppendicesAppendix A: Applicable SAE Standards 33Appendix B: Federal Certificationand Record-Keeping Requirements1.Why UseThis Service Guide?1.1 PurposeThe purpose of this book is to help automotive
10、 air-conditioning service professionals comply with federal andstate certification requirements. To do that this book provides information about:1.) the damage that R-12 and certain other refrigerants do to the earths environment,2.) how to minimize the escape of air-conditioning refrigerants into t
11、he atmosphere,3.) the service equipment available and the importance of complying with SAE standards for bothservice practices and the selection and use of service equipment, and4.) retrofitting older air-conditioning systems to the new, environmentally friendly refrigerant, R-134a.It is assumed tha
12、t you are or will become familiar with automotive air-conditioning systems and how they arediagnosed and repaired.1.2 The Clean Air Act, You, and Your Satisfied CustomersSome of the refrigerants used in mobile air-conditioning systems are chlorofluorocarbons with chlorine in theirmolecular structure
13、. These chlorofluorocarbons are excellent refrigerants and have been selected for use inmobile systems specifically because of their ability to perform well in mobile air conditioners. The mostpopular of these, R-12, has been used in virtually every passenger car air-conditioning system produced thr
14、oughthe 1991 model year. As a family, the chlorofluorocarbons carry the abbreviation “CFC.“ Within the chemicalindustry, R-12 is known as CFC-12.Unfortunately, chlorofluorocarbons do multiple damage to the environment:1.) The chlorine in the CFCs reacts with and destroys the earths protective layer
15、of ozone.2.) CFCs act as a filter by absorbing certain wavelengths of light in a manner similar to that of greenhouseglass, contributing to global warming.Because of the severe global impact of a depletion in the ozone layer, 68 nations had ratified the “MontrealProtocol“ by the fall of 1991. This p
16、rotocol calls for extensive international efforts to reduce and eventuallyeliminate the CFCs that damage the ozone layer. (Ozone-damaging CFCs include CFC-11, 12, 113, 114, and115.)Recent atmospheric tests have found that the damage to the ozone layer is increasing at a rate much faster thanwas beli
17、eved to be the case when the protocol was signed. Therefore, the steps agreed on in the MontrealProtocol are being implemented by various nations at an accelerated pace.1In the United States, the Clean Air Act and follow-up regulations which took effect on November 15, 1991,require that service oper
18、ations minimize or prevent the release of R-12 and other ozone-damaging refrigerantsinto the atmosphere. At the same time, a progressive tax has been placed on R-12 to make virgin refrigerantmore and more expensive in order to reduce customer demand for this material. R-12 production is beingphased
19、down. Ultimately, U.S. production of R-12 will be banned completely after December 31, 1995. Ger-many, Denmark, and the Netherlands were expected to ban production and use of R-12 by the end of 1994.This places the burden on the air-conditioning service technician to capture and reuse as much of the
20、 refrigerantalready in a vehicles air-conditioning system as possible. This must be done properly so that the customersair-conditioning system has “like new“ performance and durability. Improper capture and reuse of the refriger-ant, or the use of the wrong refrigerant, could lead to early system fa
21、ilure and an unhappy customer.This guide will help you take good care of both the environment and your customer.1.3 The Environmental Impact of Some RefrigerantsThe traditional refrigerants, including R-12, contain chlorine. Upon exposure to sunlight at high altitudes,CFCs break down, releasing the
22、chlorine. The chlorine then attacks and destroys the ozone in the stratosphere.CFCs can remain in the atmosphere for 100 years or more, slowly releasing ozone-damaging chlorine. There-fore, R-12 released today will still be doing environmental damage long after the service technician who re-leased i
23、t has retired.The ozone layer protects the earths surface from most of the ultraviolet rays of the sun. Some of these rays,ultraviolet “B,“ are the ones that cause skin cancer and cataracts in humans, and damage crops and many otherliving organisms. Mankinds release of CFCs over the last 40 or so ye
24、ars has caused very rapid changes in theozone layer and the level of ultraviolet radiation reaching us. Every 1% decrease in the ozone layer increasesthe ultraviolet radiation reaching the earth by 1.5 to 2%. This rate of change in the intensity of ultraviolet raysis too fast for living organisms to
25、 adapt. For example, if current trends continue unabated, the number of humancataract cases expected by the year 2075 will increase by 18 million. Actions required by the Montreal Protocolto reverse this trend are expected to reduce the projected number of cases significantly.The increased penetrati
26、on of ultraviolet rays to the earths surface also increases the generation of ground-levelozone. While ozone in the stratosphere helps protect the earth, ozone at ground level is a health hazard. Whenbreathed, ozone irritates the air passages in our noses and throats as well as the surface of our lu
27、ngs.CFCs also contribute to global warming. Global warming is caused by some gases in the atmosphere which actlike the glass in a greenhouse. Greenhouses are warmed by the sun because the glass allows the radiant heatfrom the sun to enter the greenhouse, but prevents the radiant heat of the earth fr
28、om leaving. Because they havethe same capability as glass to pass or block radiant energy from the sun or the earth, respectively, these gaseshave become known as “Greenhouse Gases.“ Warming of the earth due to increases in the amount of thesegases in the atmosphere has been called “The Greenhouse E
29、ffect.“CFCs are extremely durable in the atmosphere. Some are capable of lasting for over 100 years. Because theyare so durable, their concentration can increase substantially over time, accelerating global warming and ozonedestruction even further. The fewer CFCs released to the atmosphere, the bet
30、ter.Mobile air-conditioning systems are by far the largest user of CFCs in the United States. Over 80% of all carssold in the United States for many years have been fitted with air conditioning. Each system contains at least 1.5pounds of refrigerant that, if released into the air, will eventually de
31、stroy several times its weight in ozone.2Therefore, mobile air-conditioning system production and maintenance have justly attracted a great deal ofattention in the fight to preserve the remaining ozone layer.1.4 Industry Efforts to Solve the ProblemYou might ask, “Why not just replace the CFCs in my
32、 customers cars with an environmentally safe refrigerantthe next time they need AC service?“ Good question. The auto manufacturers and refrigeration industry areworking to develop substitute refrigerants and retrofit systems to allow the replacement of R-12 with a moreenvironmentally friendly materi
33、al. Refrigerants containing reduced amounts of chlorine, thehydrochlorofluorocarbons (HCFCs), have been proposed for this application. These or any other substituterefrigerants are expected to also require the replacement of many pieces of the air-conditioning system. It is notexpected that a simple
34、 direct or “drop-in“ substitute for R-12 will ever be developed.Under no circumstance must refrigerant other than the one approved by the vehicle or system manufac-turer be used in a mobile air-conditioning system. If a refrigerant other than R-12 is to be used in anolder system, its use must be acc
35、ompanied by all of the system changes recommended by the vehicle orsystem manufacturer. All equipment and instructions necessary to accomplish the recommended changescan be expected to be supplied by the vehicle or system manufacturer.Retrofit systems are being developed by the vehicle manufacturers
36、 to retrofit R-12 systems with R-134a. Thesesystems include new lubricant as well as any required hoses, seals, and dessicant in addition to the less environ-mentally damaging refrigerant. As will be discussed, mobile air-conditioning systems are designed as a system.Each part must be compatible wit
37、h all other system components. So, too, will the retrofit systems be completedesigns. All of the manufacturers components must be utilized in order to accomplish a satisfactory retrofit.Partial application of only a few elements of the retrofit system is likely to lead to failure, poor performance,
38、orboth. Either case will guarantee an unhappy customer.Refrigerant manufacturers and the auto industry have developed a replacement for CFCs in new car air-condi-tioning systems. The refrigerant to be used in new, environmentally friendlier systems is a refrigerant contain-ing hydrogen instead of ch
39、lorine. This refrigerant is a member of the hydrofluorocarbon (HFC) refrigerantfamily. The HFC of choice is HFC-134a, also known as R-134a. Phase-in of R-134a began with the 1992model year and is expected to be completed in Europe, Japan, and the United States by the 1996 model year.These environmen
40、tally safer refrigerant families carry several different trade names. Because such trade namesrefer to broad families of refrigerants, they will not be referred to in this guide. It is important that refrigerantsbe designated by their specific compound name in order to ensure proper air-conditioning
41、 system service.HFCs and HCFCs offer reduced environmental damage in two ways. First, the hydrogen in these refrigerantscauses them to be much less stable in the atmosphere than CFCs. Their lifetime in the atmosphere is only 2 to25 years, 4 to over 50 times shorter than the CFCs. While the HCFCs sti
42、ll contain chlorine, the increasedchemical instability of HCFC in the atmosphere causes the chlorine to be dispersed at lower altitudesbelowthe ozone layer. Second, the HFCs are still greenhouse gases, but much less so. Figure 1 presents the relativeenvironmental damage potentials of CFC-12, HFC-134
43、a, and possible retrofit refrigerants. CFC-11, once com-monly used as a flushing agent for mobile air-conditioning systems, is also shown.Because the HCFCs still contain chlorine, they are considered more as a transition material than a long-termsolution to the problem. Some of the refrigerants show
44、n in Figure 1 may be blended together and used inconjunction with approved retrofit components in older systems, for example. However, atmospheric datacollected since the 1990 Montreal Protocol was first signed indicates that the ozone problem is more severe thanoriginally believed. This increased c
45、oncern may disallow HCFCs altogether.3As previously mentioned, it is not possible to just replace harmful CFC refrigerant with an environmentallysafer material such as R-134a. Air-conditioning equipment is designed as a system. The refrigerant and itsthermodynamic, physical, and chemical properties
46、are a key factor in the overall system design. If you were tojust replace R-12 with R-134a, for example, your customers air-conditioning systems would perform poorly atlow speeds such as in city traffic. Eventually the compressor and other system parts would fail due to chemicalattack, overpressure,
47、 and poor lubrication.Figure 1Relative Environmental Damage Potential of Current and PossibleRefrigerants and CFC-11, a Flushing AgentYour best choice is to properly capture and recycle to industry standards any refrigerant that you use. RecyclingCFC and HCFC refrigerants was required nationwide by
48、the EPA as of January 1, 1992, although some statesrequired it earlier. The EPA requires the recovery and recycling of HFCs (R-134a) beginning November 15,1995. Recovery and recycling will minimize the amount of refrigerant released from your service operationsand will allow you to provide environme
49、ntally sound service while keeping your customers air-conditioningsystems operating satisfactorily.Since the production of CFCs will be banned, recovery and recycling of refrigerant and the use of substituterefrigerants and retrofit systems will eventually be the only way of maintaining systems originally designed forImportant NoteNo refrigerant other than R-12 should be used in an older passenger car air-conditioning systemunless it is specifically recommended as a substitute for use in the system you are servicing by theoriginal vehicle or air-conditioning system manufacturer.
