ASE 7 - Heating, Ventilation, & Air Conditioningfaculty.ccbcmd.edu/~smacadof/Books/A7Student... · retrofit on an automotive air conditioning system. 2. Be able to list four considerations

ASE 7 - Heating, Ventilation, & Air Conditioning

Module 7Retrofitting

AcknowledgementsGeneral Motors, the IAGMASEP Association Board of Directors, and Raytheon ProfessionalServices, GM's training partner for GM's Service Technical College wish to thank all of thepeople who contributed to the GM ASEP/BSEP curriculum development project 2002-3. Thisproject would not have been possible without the tireless efforts of many people. Weacknowledge:

• The IAGMASEP Association members for agreeing to tackle this large project to createthe curriculum for the GM ASEP/BSEP schools.

• The IAGMASEP Curriculum team for leading the members to a single vision andimplementation.

• Direct contributors within Raytheon Professional Services for their support of translatinga good idea into reality. Specifically, we thank:

– Chris Mason and Vince Williams, for their leadership, guidance, and support.– Media and Graphics department under Mary McClain and in particular, Cheryl

Squicciarini, Diana Pajewski, Lesley McCowey, Jeremy Pawelek, & NancyDeSantis.

– For his help on the Heating, Ventilation, and Air Conditioning curriculum volume,Subject Matter Expert, Brad Fuhrman, for his wealth of knowledge.

Finally, we wish to recognize the individual instructors and staffs of the GM ASEP/BSEPColleges for their contribution for reformatting existing General Motors training material, addingcritical technical content and the sharing of their expertise in the GM product. Separatecommittees worked on each of the eight curriculum areas. For the work on this volume, wethank the members of the Heating, Ventilation, and Air Conditioning committee:

– Steve Ash, Sinclair Community College– Warren Farnell, Northhampton Community College– Rick Frazier, Owens Community College– Marvin Johnson, Brookhaven College– Chris Peace, J. Sargeant Reynolds Community College– Vince Williams, Raytheon

ContentsModule 7 – RetrofittingAcknowledgements .......................................................................................... 2Introduction ...................................................................................................... 4Objectives ........................................................................................................ 4

Lesson 1. Determining When to Retrofit ........................................................................ 6Lesson 2. The Legal Requirements When Retrofitting ................................................... 8Lesson 3. The Retrofit Procedure ................................................................................... 9Post-Test ....................................................................................................................... 18Exercise # 1 .................................................................................................................. 20Exercise 2 ..................................................................................................................... 22

© 2002 General Motors CorporationAll Rights Reserved

ASE 7 - HVAC

Module 7 -Retrofitting

7-4

Student WorkbookIntroductionThis module will introduce you to retrofitting R-12 refrigeration systems.You will learn the legal requirements of retrofitting, the criteria to use whendeciding to retrofit a refrigeration system, and the correct retrofitprocedures as recommended by General Motors.As you may know, the production of R-12 has been phased out. WhileR-12 is no longer produced and the supply has decreased, it still may beavailable for some time in the future. This is due to recovery and recyclingefforts. However, as the supply of R-12 has decreased the cost hasincreased significantly.Retrofitting R-12 systems to R-134a systems has become more commonas the cost of R-12 has risen. In this module you will learn how to performa retrofit and be able to help the customer decide whether a retrofit is theappropriate repair for their vehicle.

Objectives1. Be able to explain the legal requirements necessary to perform a

retrofit on an automotive air conditioning system.2. Be able to list four considerations when making a decision to retrofit a

vehicle.3. Be able to determine which components are compatible with R-12 and

which components should be changed.4. Have knowledge of the possible problems that could result from a

retrofit to R-134a.5. Be able to perform a retrofit, following General Motor's guidelines and

procedures.

NATEF Area VII.1. Identify and recover AC refrigerant.2. Evacuate an AC system.3. Follow Federal and local guidelines for retrofit procedures.4. Leak test AC system determine needed repairs.5. Inspect, repair, or replace AC system hoses, lines, fittings, filters, and

seals.


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7-5

Student WorkbookSTC Tasks:1. Identify when a retrofit should be performed.2. Identify equipment and parts used in the retrofitting process.3. Describe the correct procedure for R-12 recovery.4. Describe the correct procedures for preparing the system for R-134a.5. Describe the correct procedure for charging, lubricating and labeling a

retrofitted AC system.


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7-6

Student WorkbookLesson 1. Determining When to RetrofitThere are basically four criteria to determine when to retrofit a vehicle.These criteria should be considered and discussed with the customerbefore performing a retrofit. Remember that although a retrofitted R-12system may perform satisfactory, it was designed for R-12. A system thatwas designed for R-12 will usually perform better with R-12 then with R-134a. The criteria that you should follow when retrofitting an R-12 systemto R-134a are as follows.1. Availability of R-122. Cost of R-123. Cost of the repair4. Compatibility of the vehicle to retrofitting.Obviously, if or when R-12 is no longer available, then the decision toretrofit a vehicle to R-134a is the only alternative. However, at this timethere still is a supply of R-12 available for servicing R-12 systems. As longas R-12 is available you need to involve the customer in deciding if aretrofit should be performed. While the AC system may perform to thecustomer's satisfaction, in some cases in extreme climate conditions suchas high temperature and humidity, some retrofitted systems do notperform as well as when they were operated with R-12.As the cost of R-12 continues to rise the economics of retrofitting a vehicleimprove. In some cases the cost to retrofit an AC system may be less thenservicing the vehicle with R-12. The customer may choose to retrofit to R-134a to reduce the cost of the repair or to ensure that if any future repairsare required, the system will be easier to service. The customer should beinvolved in the decision of whether to retrofit the vehicle or continue toservice the system with R-12 if it is available.The cost of the repair may be a determining factor when deciding toretrofit. The more extensive the repair, such as compressor replacementmakes the decision to retrofit more economical. On the other hand, if a R-12 system simply needs a small leak repaired and the rest of the systemperforms well, then a retrofit may not be warranted.


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7-7

Student WorkbookSome older vehicle's AC systems may not perform as well when retrofittedto R-134a. Depending on the design of the AC system and thegeographical location of the vehicle some vehicles should not beretrofitted if possible. In some instances larger trucks equipped with rearAC have not performed satisfactorily in some areas of the country. Makesure that you check on possible problems on certain vehicles beforerecommending a retrofit.Never take the decision to retrofit a vehicle to R-134a lightly. Remember toinvolve the customer in the decision making process after you haveexplained all of the options to him or her. Many vehicles have beensuccessfully retrofitted with satisfactory performance, however somevehicles do not perform to customer expectations after a retrofit. Byinvolving the customer in the decision making process you may avoid apotential customer complaint after performing a retrofit.


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Student WorkbookLesson 2. The Legal Requirements When RetrofittingThe EPA has established regulations for alternate refrigerants andretrofitting under the Significant New Alternatives Policy (SNAP). Theseregulations specify that:1. The original refrigerant must be removed and recovered from the

vehicle.2. Unique fittings must be installed for the refrigerant being used.3. The system must be equipped with a high-pressure cut-off switch. This

prevents unwanted venting of refrigerant to the atmosphere in case ofa system malfunction that could cause the pressures to rise beyondthe calibration of the pressure relief valve.

4. The vehicle must have installed a properly color-coded label to identifythe refrigerant.

5. If a blend refrigerant that contains R-22 is used, then the hoses mustbe replaced with barrier type hoses.

6. Refrigerant must be recovered when performing any serviceprocedures. Dedicated equipment for each type of refrigerant isrequired.

Any technician or shop performing a retrofit must follow these guidelines.There are substantial fines and penalties that the EPA may impose onboth the shop and the technician for not performing a retrofit properly.There are other blend refrigerants that the EPA has approved forautomotive use; however, GM does not recommend any refrigerants otherthan R-12 or R-134a. The use of any other refrigerant could cause systemdamage and/or unsatisfactory performance. In addition, dedicatedequipment must be used with each type of refrigerant. This limits thecustomer's choices in obtaining future AC repairs if any other blend ofrefrigerant is used. While you might have seen advertised so called "dropin" refrigerant blends, the truth is there is no such thing. Any refrigerantthat is used to replace R-12 must be installed following the guidelinesabove.As a GM technician it is your responsibility to ensure that when performinga retrofit you follow the EPA's rules and General Motors procedures. Thiswill protect you and the dealership as well as provide the best retrofitavailable for your customer. For details on the recommended GMprocedures refer to bulletin number 43-12-07E.


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7-9

Student WorkbookLesson 3. The Retrofit ProcedureThe retrofit procedure varies somewhat from vehicle model to model. Besure to refer to Bulletin number 43-12-07E to determine the exactprocedure and the necessary parts required for the retrofit. In additionsome vehicles may not be included in this bulletin. If a vehicle is notincluded in the bulletin there is no retrofit procedure for that vehicle. In thatcase the best result would be not to retrofit that vehicle.Many vehicles will require only a minimum amount of modification toperform the retrofit. Other vehicles may require more extensiveprocedures such as the addition of an auxiliary cooling fan or compressorreplacement. Make sure that you refer to the bulletin before quoting acustomer or performing the retrofit. These procedures have beendeveloped to provide the best performance when retrofitting a particularmodel. Failure to follow these procedures may result in unsatisfactoryperformance and a dissatisfied customer.1. Inspect the condition of the vehicle. Install a gauge set and measure

the pressures in the system. One of three conditions will exist.Condition #1: The system operates normally and has a sufficientcharge to operate the compressor. Proceed to the recovery process forretrofitting.Condition #2: The compressor does not operate due to low chargecondition. Leak test the system to try to determine which componentsare leaking and that may require replacement. If R-12 is available youmay want to recharge the system to determine the condition of thecompressor and other components before retrofitting.Condition #3: No charge in system. Install conversion fittings andevacuate the system for 5 minutes. Try to determine where the leak is.If this cannot be determined then partially charge the system with ½pound of R-134a and leak test. Recover the R-134a and repair anyleaks found. Proceed to the evacuation.

2. Recover the R-12 from the system. This procedure is different than thenormal R-12 recovery process. The refrigerant recovery will be throughthe high side service port only with the compressor running.

Important: The vehicle must be above 50 F to allow for the completerecovery process. Either allow the vehicle to warm up or increase theevacuation time to 30 minutes.


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7-10

Student WorkbookConnect the recovery unit to the vehicle. Drain the oil from the recoverycart before beginning the recovery process. Start the vehicle, open thewindows, turn the temperature control to full cold and engage thecompressor. Check the compressor to ensure that it is engaged. Open thehigh-side service port only and start the recovery unit. Monitor thepressure on the gauge. When the gauge reaches 15 psi, Figure 7-1,check the compressor and make sure that it has shut down. If thecompressor is still operating then turn the AC off and continue therecovery process. Leave the engine running and the blower fan on HIGH.After the recovery unit shuts off, monitor the gauges. If the gaugepressures rise above 0 psi start the recovery unit again. Repeat thisprocess until the gauge pressures stay below 0 psi after a 2 minute timeperiod. Remove the R-12 recovery unit.

Figure 7-1, When the low-side gauge reaches 15 psi turn the AC off if thecompressor is still running.

3. Install the service port fittings. A special tool kit is available J39500-275to aid in the removal and or repair of the R-12 fittings, Figure 7-2.

Figure 7-2, A/C Retrofit Service Tool Kit(Part #39500-250)


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7-11

Student Workbooka. Remove the caps from the R-12 fittings. Clean any dirt or greasefrom the port threads using the thread cleaning wire brush J41265,Figure 7-3.

If the threads are damaged use the port thread restorer J41266 low sideor J41267 high side to repair the threads, Figure 7-4.

Figure 7-3, Clean the threads.

Figure 7-4, If the threads are damaged restore them with the thread restored.


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7-12

Student WorkbookInstall the selected fittings on the low side and the high side service ports.Depending on the location of the service ports you may need to useeither the straight or 90 degree fittings to provide adequate clearance toconnect your service equipment. In the case of a vehicle that does nothave a high side service port available, then a saddle-type clamp must beused, Figure 7-5.

Figure 7-5, These fittings are available through parts.Check Bulletin #43-12-07E for part numbers.

Any existing R-12 port that is not used must be rendered inoperative.Place several drops of a thread-locking compound, such as Loctite 242 inthe valve core and onto the cap threads. Secure the cap and let it set for15 minutes, Figure 7-6.

Figure 7-6, Use Loctite to render any unused R-12 service ports inoperative.

4. Install any additional parts that are needed.


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7-13

Student Workbooka. Compressors- The compressor does not have to be replaced aspart of a normal retrofit procedure unless indicated in thecompressor replacement chart in bulletin #43-12-07E. If thecompressor needs to be replaced due to compressor failure makesure that the replacement compressor is designed for R-134arefrigerant, Figure 7-7.

Figure 7-7, The label on the compressor should indicate whether it isdesigned for R-12 or R-134a.

b. Accumulator/Drier- If the accumulator/drier is more than five yearsold it should be replaced to ensure that any moisture remaining inthe system may be removed. All replacement accumulator/driersshould be compatible with R-134a.

c. High Pressure Cut-Off Switch (HPCOS)- Most truck and some1984-1893 B and D cars require a high-pressure cut-off switch beadded to the vehicle. This protects the refrigeration system in theevent of excessive high-pressures which may occur during longidles at very high temperatures. The high-pressure cut-off switchwill electrically shut off the compressor when the high sidepressures are too high. This will prevent any accidental venting ofrefrigerant should the pressures rise above the calibration of thehigh-pressure relief valve. Refer to bulletin #43-12-07E for partnumbers and applications for these switches.

5. Evacuate the system using the ACR4 or equivalent piece ofequipment. Evacuate the system for a minimum of 15 minutes. A 30minute evacuation would be better. The equipment must be capable ofpulling the vacuum down to 28 to 29 in. Hg at sea level. Reduce this by1 in. Hg. for each 1000 ft. above sea level. After the vacuum pump hasshut off, monitor the low-side gauge for a period of 2 minutes. Thevacuum should be maintained; Figure 7-8, if not, there is a leak in thesystem. You will have to perform a partial charge with R-134a and leaktest the system.

After connecting the cart open only the high-side service port. Unlike thenormal evacuation process you will only evacuate through the high side.

R-134a COMPRESSOR


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7-14

Student Workbook

Figure 7-8, Monitor the vacuum for 2 minutes after the vacuum pump shuts off.

After the evacuation is complete and you have determined that the systemretains vacuum, oil will need to be added to the system before charging.Refer to the bulletin #43-12-07E to determine the type of oil to add. If youreplaced the compressor and it was shipped with oil, no additional oil willbe needed. If the compressor is a V-5 compressor it will require a specialretrofit oil. If this oil is not available then the compressor must be replaced.

Note: Depending on the equipment that you are using the oil may beinjected into the refrigeration system at this point of the retrofit process orit could have been added to the system before the evacuation processwas begun. Most important is that you add the correct type and amount ofoil to the system before the charging process.

6. Determine the correct amount of R-134a that the system must becharged with. This amount is usually between 80% to 90% of theoriginal system capacity. To determine the correct amount you may usethe formula shown below.

R-134a = (R-12 x .9) -.25


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7-15

Student WorkbookYou may also refer to the table shown below to determine the correctcharge amount, Figure 7-9.Follow the directions on the charging equipment and charge the ACsystem with the correct amount of R-134a. Close the service gauge valveson the equipment after charging is complete. Start the vehicle and turn theAC on. Verify that the pressures are within the correct operating ranges forthat vehicle per the service manual.To ensure an accurate charge amount it isimportant to clear any refrigerant left inthe charging station hoses. Remove thehigh side hose from the vehicle. Openboth the low-side and the high-sideservice valves on the charging equipmentand allow the compressor to draw in anyremaining refrigerant in the hoses.

Figure 7-9, R-12 to R-134aConversion chart.

After both gauges are at the normal low side pressure readings close bothservice valves on the charging station. Remove the charging hoses fromthe vehicle and install the service port caps on the vehicle's servicefittings.7. Leak test the service port

fittings, any connections thatwere opened, and any partsthat were replaced using leakdetector J39400 orequivalent, Figure 7-10.

Figure 7-10, Thoroughly leak testthe AC system.


ASE 7 - HVAC


7-16

Student Workbook8. Fill out and install the retrofit label, Figure 7-11 and 7-12.

Figure 7-11, R-134a retrofit label. Note the blue color.

Figure 7-12, Install the label in a prominent area.


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7-17

Student WorkbookFill in the new label using a ballpoint pen or a typewriter. Select a locationon the vehicle that the label will be clearly visible. If possible an area nearthe existing R-12 label. Do not remove or destroy the existing R-12 labelon the vehicle. Use an indelible pen to black out the existing R-12 chargeamount, Figure 7-13.

Figure 7-13, Blacken out the R-12 charge amount.


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7-18

Student WorkbookPost-TestRead each question carefully and choose the correct response.

1. Under the SNAP rule, which of the following have to be performedwhen retrofitting?a. Install unique fittingsb. Install a retrofit labelc. Install a high pressure cut-off switch if not so equippedd. All of the above

2. The accumulator/drier must always be replaced whenever a retrofit isperformed.a. Trueb. False

3. A vehicle is being retrofitted. The R-12 capacity of the system was2.5 lbs of R-12. What should the R-134a charge amount be?a. 1.5 lbsb. 2.0 lbsc. 2.25 lbsd. 2.5 lbs

4. When recovering the R-12 from a system that is going to be retrofittedthe recovery process should be performed when the vehicle andcompressor are running and the recovery should be through:a. the low-side onlyb. both the low-side and the high-sidec. the high-side onlyd. any of the above

5. When performing a retrofit on a vehicle with a V-5 compressor, if thecompressor must be replaced a special V-5 retrofit oil must be used.a. Trueb. False


ASE 7 - HVAC


7-19

Student Workbook6. The retrofit label should be placed over the R-12 label wheneverpossible.a. Trueb. False

7. When evacuating the AC system after the installation of the R-134aservice port fittings, evacuation should be performed through the:a. Low-side onlyb. High-side onlyc. Both the low-side and the high-sided. Any of the above

8. The old R-12 refrigerant label should be completely blacked out afterperforming a retrofit and installing the retrofit label.a. Trueb. False

9. Before performing a retrofit the technician discovers a leaking hose onthe vehicle. Technician A says that if replacing the hose it must be abarrier hose. Technician B says that a barrier hose is not requiredbecause the other hoses on the vehicle are the non-barrier type. Whois correct?a. Technician Ab. Technician Bc. Both Technician A and Bd. Neither Technician A or B


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7-20

Student WorkbookExercise # 1Directions: Answer the following questions using the module #7workbook.

1. List four criteria to follow when deciding to perform a retrofit.Page _______________________________________________________________________________________________________

2. When performing a retrofit, if the vehicle is not equipped with a________________ switch one must be installed.Page _______________________________________________________________________________________________________

3. Each refrigerant approved by the EPA must have unique _________installed on the vehicle.Page _______________________________________________________________________________________________________

4. What is the GM bulletin number that covers the retrofit procedures?Page _______________________________________________________________________________________________________

5. The vehicle must be above _________ F before recovering therefrigerant.Page _______________________________________________________________________________________________________

6. When recovering the refrigerant the compressor should be _______and the refrigerant should be recovered through the _________ only.

Page _______________________________________________________________________________________________________


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7-21

Student Workbook7. List three different fittings that are available when retrofitting.Page _______________________________________________________________________________________________________

8. During the evacuation process the equipment must be capable ofpulling the vacuum down to ______ to _______ in. Hg.Page _______________________________________________________________________________________________________

9. The amount of R-134a charge should normally be between _______and _______ of the R-12 charge amount.Page _______________________________________________________________________________________________________

10.R-134a retrofit labels are __________ in color.Page _______________________________________________________________________________________________________


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Student WorkbookExercise 2Directions: Your instructor will assign you the model year, model, andengine of a GM vehicle that was equipped with an R-12 system. Using theappropriate service information and the retrofit bulletin 43-12-07E answerthe following questions.

1. Is this vehicle listed on the retrofit bulletin? Yes No

2. Does the compressor need to be replaced on this vehicle?Yes No

If Yes what is the part number of the compressor. ________________

3. Does this vehicle need a HPCS installed? Yes No

4. What is the R-12 charge amount for this vehicle. ________________

5. What would be the R-134a charge amount for this vehicle. ________

6. List the part numbers of the high and low side R-134a fittings that youwould use. _____________________________________________

7. List the part number of the oil that you would use. _______________

8. How much oil would you add to the system? ___________________

9. Are there any other components that the bulletin recommendschanging or adding to this vehicle? Yes No

If Yes list the additional parts that are required. ______________________________________________________________________

10.List the part number for the retrofit label. _____________________

ASE 7 - Heating, Ventilation, & Air Conditioningfaculty.ccbcmd.edu/~smacadof/Books/A7Student... · retrofit on an automotive air conditioning system. 2. Be able to list four considerations

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