ASE 7 - Heating, Ventilation, & Air Conditioning. Module 7 Retrofitting

Transcription

1 ASE 7 - Heating, Ventilation, & Air Conditioning Module 7

2 Acknowledgements General Motors, the IAGMASEP Association Board of Directors, and Raytheon Professional Services, GM's training partner for GM's Service Technical College wish to thank all of the people who contributed to the GM ASEP/BSEP curriculum development project This project would not have been possible without the tireless efforts of many people. We acknowledge: The IAGMASEP Association members for agreeing to tackle this large project to create the curriculum for the GM ASEP/BSEP schools. The IAGMASEP Curriculum team for leading the members to a single vision and implementation. Direct contributors within Raytheon Professional Services for their support of translating a 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, & Nancy DeSantis. 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/BSEP Colleges for their contribution for reformatting existing General Motors training material, adding critical technical content and the sharing of their expertise in the GM product. Separate committees worked on each of the eight curriculum areas. For the work on this volume, we thank 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

3 Module 7 Contents Acknowledgements... 2 Introduction... 4 Objectives... 4 Lesson 1. Determining When to Retrofit... 6 Lesson 2. The Legal Requirements When... 8 Lesson 3. The Retrofit Procedure... 9 Post-Test Exercise # Exercise

4 Introduction This module will introduce you to retrofitting R-12 refrigeration systems. You will learn the legal requirements of retrofitting, the criteria to use when deciding to retrofit a refrigeration system, and the correct retrofit procedures as recommended by General Motors. As you may know, the production of R-12 has been phased out. While R-12 is no longer produced and the supply has decreased, it still may be available for some time in the future. This is due to recovery and recycling efforts. However, as the supply of R-12 has decreased the cost has increased significantly. R-12 systems to R-134a systems has become more common as the cost of R-12 has risen. In this module you will learn how to perform a retrofit and be able to help the customer decide whether a retrofit is the appropriate repair for their vehicle. Objectives 1. 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. 7-4

5 STC 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. 7-5

6 Lesson 1. Determining When to Retrofit There are basically four criteria to determine when to retrofit a vehicle. These criteria should be considered and discussed with the customer before performing a retrofit. Remember that although a retrofitted R-12 system may perform satisfactory, it was designed for R-12. A system that was 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 system to R-134a are as follows. 1. Availability of R Cost of R Cost of the repair 4. Compatibility of the vehicle to retrofitting. Obviously, if or when R-12 is no longer available, then the decision to retrofit a vehicle to R-134a is the only alternative. However, at this time there still is a supply of R-12 available for servicing R-12 systems. As long as R-12 is available you need to involve the customer in deciding if a retrofit should be performed. While the AC system may perform to the customer's satisfaction, in some cases in extreme climate conditions such as high temperature and humidity, some retrofitted systems do not perform as well as when they were operated with R-12. As the cost of R-12 continues to rise the economics of retrofitting a vehicle improve. In some cases the cost to retrofit an AC system may be less then servicing 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 repairs are required, the system will be easier to service. The customer should be involved in the decision of whether to retrofit the vehicle or continue to service the system with R-12 if it is available. The cost of the repair may be a determining factor when deciding to retrofit. The more extensive the repair, such as compressor replacement makes 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 system performs well, then a retrofit may not be warranted. 7-6

7 Some older vehicle's AC systems may not perform as well when retrofitted to R-134a. Depending on the design of the AC system and the geographical location of the vehicle some vehicles should not be retrofitted if possible. In some instances larger trucks equipped with rear AC have not performed satisfactorily in some areas of the country. Make sure that you check on possible problems on certain vehicles before recommending a retrofit. Never take the decision to retrofit a vehicle to R-134a lightly. Remember to involve the customer in the decision making process after you have explained all of the options to him or her. Many vehicles have been successfully retrofitted with satisfactory performance, however some vehicles do not perform to customer expectations after a retrofit. By involving the customer in the decision making process you may avoid a potential customer complaint after performing a retrofit. 7-7

8 Lesson 2. The Legal Requirements When The EPA has established regulations for alternate refrigerants and retrofitting under the Significant New Alternatives Policy (SNAP). These regulations 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 of a system malfunction that could cause the pressures to rise beyond the calibration of the pressure relief valve. 4. The vehicle must have installed a properly color-coded label to identify the refrigerant. 5. If a blend refrigerant that contains R-22 is used, then the hoses must be replaced with barrier type hoses. 6. Refrigerant must be recovered when performing any service procedures. Dedicated equipment for each type of refrigerant is required. Any technician or shop performing a retrofit must follow these guidelines. There are substantial fines and penalties that the EPA may impose on both the shop and the technician for not performing a retrofit properly. There are other blend refrigerants that the EPA has approved for automotive use; however, GM does not recommend any refrigerants other than R-12 or R-134a. The use of any other refrigerant could cause system damage and/or unsatisfactory performance. In addition, dedicated equipment must be used with each type of refrigerant. This limits the customer's choices in obtaining future AC repairs if any other blend of refrigerant is used. While you might have seen advertised so called "drop in" refrigerant blends, the truth is there is no such thing. Any refrigerant that is used to replace R-12 must be installed following the guidelines above. As a GM technician it is your responsibility to ensure that when performing a retrofit you follow the EPA's rules and General Motors procedures. This will protect you and the dealership as well as provide the best retrofit available for your customer. For details on the recommended GM procedures refer to bulletin number E. 7-8

9 Lesson 3. The Retrofit Procedure The retrofit procedure varies somewhat from vehicle model to model. Be sure to refer to Bulletin number E to determine the exact procedure and the necessary parts required for the retrofit. In addition some vehicles may not be included in this bulletin. If a vehicle is not included in the bulletin there is no retrofit procedure for that vehicle. In that case the best result would be not to retrofit that vehicle. Many vehicles will require only a minimum amount of modification to perform the retrofit. Other vehicles may require more extensive procedures such as the addition of an auxiliary cooling fan or compressor replacement. Make sure that you refer to the bulletin before quoting a customer or performing the retrofit. These procedures have been developed to provide the best performance when retrofitting a particular model. Failure to follow these procedures may result in unsatisfactory performance 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 sufficient charge to operate the compressor. Proceed to the recovery process for retrofitting. Condition #2: The compressor does not operate due to low charge condition. Leak test the system to try to determine which components are leaking and that may require replacement. If R-12 is available you may want to recharge the system to determine the condition of the compressor and other components before retrofitting. Condition #3: No charge in system. Install conversion fittings and evacuate the system for 5 minutes. Try to determine where the leak is. If this cannot be determined then partially charge the system with ½ pound of R-134a and leak test. Recover the R-134a and repair any leaks found. Proceed to the evacuation. 2. Recover the R-12 from the system. This procedure is different than the normal R-12 recovery process. The refrigerant recovery will be through the high side service port only with the compressor running. Important: The vehicle must be above 50 F to allow for the complete recovery process. Either allow the vehicle to warm up or increase the evacuation time to 30 minutes. 7-9

10 Connect the recovery unit to the vehicle. Drain the oil from the recovery cart before beginning the recovery process. Start the vehicle, open the windows, turn the temperature control to full cold and engage the compressor. Check the compressor to ensure that it is engaged. Open the high-side service port only and start the recovery unit. Monitor the pressure on the gauge. When the gauge reaches 15 psi, Figure 7-1, check the compressor and make sure that it has shut down. If the compressor is still operating then turn the AC off and continue the recovery process. Leave the engine running and the blower fan on HIGH. After the recovery unit shuts off, monitor the gauges. If the gauge pressures rise above 0 psi start the recovery unit again. Repeat this process until the gauge pressures stay below 0 psi after a 2 minute time period. Remove the R-12 recovery unit. Figure 7-1, When the low-side gauge reaches 15 psi turn the AC off if the compressor is still running. 3. Install the service port fittings. A special tool kit is available J to 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 # ) 7-10

11 a. Remove the caps from the R-12 fittings. Clean any dirt or grease from the port threads using the thread cleaning wire brush J41265, Figure 7-3. Figure 7-3, Clean the threads. If the threads are damaged use the port thread restorer J41266 low side or J41267 high side to repair the threads, Figure 7-4. Figure 7-4, If the threads are damaged restore them with the thread restored. 7-11

12 Install 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 use either the straight or 90 degree fittings to provide adequate clearance to connect your service equipment. In the case of a vehicle that does not have a high side service port available, then a saddle-type clamp must be used, Figure 7-5. Figure 7-5, These fittings are available through parts. Check Bulletin # E 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 in the valve core and onto the cap threads. Secure the cap and let it set for 15 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. 7-12

13 a. Compressors- The compressor does not have to be replaced as part of a normal retrofit procedure unless indicated in the compressor replacement chart in bulletin # E. If the compressor needs to be replaced due to compressor failure make sure that the replacement compressor is designed for R-134a refrigerant, Figure 7-7. R-134a COMPRESSOR Figure 7-7, The label on the compressor should indicate whether it is designed for R-12 or R-134a. b. Accumulator/Drier- If the accumulator/drier is more than five years old it should be replaced to ensure that any moisture remaining in the system may be removed. All replacement accumulator/driers should be compatible with R-134a. c. High Pressure Cut-Off Switch (HPCOS)- Most truck and some B and D cars require a high-pressure cut-off switch be added to the vehicle. This protects the refrigeration system in the event of excessive high-pressures which may occur during long idles at very high temperatures. The high-pressure cut-off switch will electrically shut off the compressor when the high side pressures are too high. This will prevent any accidental venting of refrigerant should the pressures rise above the calibration of the high-pressure relief valve. Refer to bulletin # E for part numbers and applications for these switches. 5. Evacuate the system using the ACR4 or equivalent piece of equipment. Evacuate the system for a minimum of 15 minutes. A 30 minute evacuation would be better. The equipment must be capable of pulling the vacuum down to 28 to 29 in. Hg at sea level. Reduce this by 1 in. Hg. for each 1000 ft. above sea level. After the vacuum pump has shut off, monitor the low-side gauge for a period of 2 minutes. The vacuum should be maintained; Figure 7-8, if not, there is a leak in the system. You will have to perform a partial charge with R-134a and leak test the system. After connecting the cart open only the high-side service port. Unlike the normal evacuation process you will only evacuate through the high side. 7-13

14 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 system retains vacuum, oil will need to be added to the system before charging. Refer to the bulletin # E to determine the type of oil to add. If you replaced the compressor and it was shipped with oil, no additional oil will be needed. If the compressor is a V-5 compressor it will require a special retrofit 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 be injected into the refrigeration system at this point of the retrofit process or it could have been added to the system before the evacuation process was begun. Most important is that you add the correct type and amount of oil to the system before the charging process. 6. Determine the correct amount of R-134a that the system must be charged with. This amount is usually between 80% to 90% of the original system capacity. To determine the correct amount you may use the formula shown below. R-134a = (R-12 x.9)

15 You may also refer to the table shown below to determine the correct charge amount, Figure 7-9. Follow the directions on the charging equipment and charge the AC system with the correct amount of R-134a. Close the service gauge valves on the equipment after charging is complete. Start the vehicle and turn the AC on. Verify that the pressures are within the correct operating ranges for that vehicle per the service manual. To ensure an accurate charge amount it is important to clear any refrigerant left in the charging station hoses. Remove the high side hose from the vehicle. Open both the low-side and the high-side service valves on the charging equipment and allow the compressor to draw in any remaining refrigerant in the hoses. Figure 7-9, R-12 to R-134a Conversion chart. After both gauges are at the normal low side pressure readings close both service valves on the charging station. Remove the charging hoses from the vehicle and install the service port caps on the vehicle's service fittings. 7. Leak test the service port fittings, any connections that were opened, and any parts that were replaced using leak detector J39400 or equivalent, Figure Figure 7-10, Thoroughly leak test the AC system. 7-15

16 8. Fill out and install the retrofit label, Figure 7-11 and Figure 7-11, R-134a retrofit label. Note the blue color. Figure 7-12, Install the label in a prominent area. 7-16

17 Fill in the new label using a ballpoint pen or a typewriter. Select a location on the vehicle that the label will be clearly visible. If possible an area near the existing R-12 label. Do not remove or destroy the existing R-12 label on the vehicle. Use an indelible pen to black out the existing R-12 charge amount, Figure Figure 7-13, Blacken out the R-12 charge amount. 7-17

18 Post-Test Read each question carefully and choose the correct response. 1. Under the SNAP rule, which of the following have to be performed when retrofitting? a. Install unique fittings b. Install a retrofit label c. Install a high pressure cut-off switch if not so equipped d. All of the above 2. The accumulator/drier must always be replaced whenever a retrofit is performed. a. True b. False 3. A vehicle is being retrofitted. The R-12 capacity of the system was 2.5 lbs of R-12. What should the R-134a charge amount be? a. 1.5 lbs b. 2.0 lbs c lbs d. 2.5 lbs 4. When recovering the R-12 from a system that is going to be retrofitted the recovery process should be performed when the vehicle and compressor are running and the recovery should be through: a. the low-side only b. both the low-side and the high-side c. the high-side only d. any of the above 5. When performing a retrofit on a vehicle with a V-5 compressor, if the compressor must be replaced a special V-5 retrofit oil must be used. a. True b. False 7-18

19 6. The retrofit label should be placed over the R-12 label whenever possible. a. True b. False 7. When evacuating the AC system after the installation of the R-134a service port fittings, evacuation should be performed through the: a. Low-side only b. High-side only c. Both the low-side and the high-side d. Any of the above 8. The old R-12 refrigerant label should be completely blacked out after performing a retrofit and installing the retrofit label. a. True b. False 9. Before performing a retrofit the technician discovers a leaking hose on the vehicle. Technician A says that if replacing the hose it must be a barrier hose. Technician B says that a barrier hose is not required because the other hoses on the vehicle are the non-barrier type. Who is correct? a. Technician A b. Technician B c. Both Technician A and B d. Neither Technician A or B 7-19

20 Exercise # 1 Directions: Answer the following questions using the module #7 workbook. 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 the refrigerant. Page 6. When recovering the refrigerant the compressor should be and the refrigerant should be recovered through the only. Page 7-20

21 7. List three different fittings that are available when retrofitting. Page 8. During the evacuation process the equipment must be capable of pulling 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 7-21

22 Exercise 2 Directions: Your instructor will assign you the model year, model, and engine of a GM vehicle that was equipped with an R-12 system. Using the appropriate service information and the retrofit bulletin E answer the 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 you would 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 recommends changing 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. 7-22