ASE 7 - Heating, Ventilation, and Air Conditioning. Module 9 Service Tools

Transcription

1 ASE 7 - Heating, Ventilation, and Air Conditioning Module 9 Service

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 9 Service Contents Acknowledgements... 2 Introduction... 4 Lesson 1: Refrigerant Leak Detection... 5 Objectives... 5 Lesson 2: ACR 2000 Familiarization Objectives Outline Lesson 2A: Causes of A/C Service Dissatisfaction Lesson 2B: New features of the ACR ACR2000 Operational Features ACR2000 Function Overview Pressure Gauges Lesson 2C: ACR2000 Maintenance and Upkeep Lesson 2D: ACR2000 Diagnosis and Service Zone Diagnostics Summary Post Test... 44

4 Introduction As a properly trained and certified A/C service technician, you will use many of the standard shop tools found in any automotive repair facility. Depending on the make and model of the vehicle that requires diagnosis and service, you may also need to use certain special service tools required for removing or installing certain A/C system components. Service procedures for specific systems should identify the special tools needed. Due to environmental regulations as well as the current use of refrigerant and lubricating oils, certain A/C service tools are dedicated for use on specific types of refrigerants. This includes the manifold gauge sets and the refrigerant recovery, recycling, evacuating and recharging equipment. An overview of the required tools and equipment for A/C system diagnosis and service includes: Refrigerant leak detectors - Various refrigerant leak detection methods have been used, ranging from soapy liquid solutions and compressed air through electronic devices to fluorescent tracer dyes. Currently GM recommends only electronic and dye leak testing. Manifold Gauge Sets - A manifold gauge set is one of the most valuable diagnostic tools for measuring both high and low side refrigerant pressures during system performance testing. If A/C service is not provided with one of the newer self-contained refrigerant handling stations, a gauge set can be used with other equipment responsible refrigerant for refrigerant recovery/evacuating/charging. Refrigerant Recovery/Recycling/Recharging Equipment - Various refrigerant handling units are available for environmentally responsible refrigerant testing and handling. GM Recommends the use of the ACR 2000 for R-134A systems. Precision Thermometer - A hand-held, probe-type precision thermometer can be inserted through an appropriate instrument panel outlet to measure the exact temperature of the discharge air during systems performance tests. Please note that this is incorporated into the ACR 2000 machine. 9-4

5 Lesson 1: Refrigerant Leak Detection Objectives NATEF Area VI. A. 1. Leak test A/C system; determine necessary action 2 Inspect the condition of discharged oil: determine necessary action 3. Determine recommended oil for system application STC Tasks: 1. Identify safety procedures to be followed when working with refrigerant systems and refrigeration systems 2. Describe the proper use of A/C service equipment utilizing approved service procedures 3. Describe approved HVAC servicing procedures 4. Describe refrigerant leak detection procedures 5. Describe refrigerant leak detection using dyes 6. Describe refrigerant leak detection using electronic leak detectors 7. Describe the impact of refrigerants on the environment 8. Identify the laws and regulations regarding approved handling of refrigerants 9. Identify system pressures using the ACR Compare System pressures to diagnostic tables 11. Identify the causes of abnormal system pressures using the pressure zone graph and diagnostic tables 12. Select the correct repair procedure in response to the pressure zone graph and diagnostic table 13. Recover refrigerant from a vehicle A/C system (ACR 2000) Evacuate a vehicle A/C system Recharge a vehicle A/C system Perform a performance test on a vehicle's A/C system Leak check an A/C system (electronic detector) Leak check an A/C system (trace dye/uv light) 9-5

6 Refrigerant Leak Detectors A highly accurate electronic leak detector is needed to detect the small molecules of R-134A as they escape from a leak. The recommended leak detection methods for today's refrigeration systems have changed substantially from the past. At the same time, because of the danger that unapproved flammable refrigerants may be in the system or that refrigerant release during testing is strictly prohibited, many leak-detection methods previously used are no longer viable for today's A/C system diagnosis and service needs. As such, methods involving soap solutions, compressed air, propane gas flame, and others are not recommended. On GM systems, the methods of choice are halogen leak detectors and fluorescent tracer dyes. Currently, GM recommends two types, the J39400-A unit and the handheld J Both types of halogen leak detectors are certified to meet stringent industry specifications for detecting leaks of as little as half an ounce per year. Each leak detector uses a heated diode sensor probe, and both have audible and visible leak detection alarms. Key features of the J A halogen leak detector include: A detector probe with a six foot flexible hose A cigarette lighter plug with a power cord and battery clamp adapter, A probe balance control, which is used to adjust the detector's sensitivity, A calibration reference bottle, and A three position switch with options for R-one-thirty-four-A, R-twelve, and gross leak. Despite the labels, the detector will identify leaks of either refrigerant at any of the settings. The settings simply increase the sensitivity of the detector. 9-6

7 To calibrate and operate detector: Follow manufacturer's specific calibration and operating instructions Warm up for at least two minutes to ensure accurate readings Slide control switch to ON, making sure airflow ball floats in probe tip Set 3-position switch to R-134a position Adjust balance control until unit ticks slowly Place probe tip over calibration reference bottle Unit is ready for system leak detection when faster audio signal is heard and flashing lamp illuminates Because refrigerant gas is heavier than air, always check for leaks on the underside of lines, fittings, and components. Slowly circle the areas, as shown on your screen. Never touch the probe tip to the part being checked. Finally, avoid using the unit in areas where its sensor heat might ignite combustibles. Figure 9-1, Halogen Leak Detector 9-7

8 Caution: Halogen leak detectors should not be used where fuel vapors or other combustibles are present. The sensor heat to about 1000 f (538 c). Vapors drawn into the probe and over the sensor could cause an explosion. Figure 9-2, Proper Leak Testing Techniques Using a Halogen Leak Detector 9-8

9 Fluorescent Dyes/UV Light The other leak detection method is the use of fluorescent dyes and ultraviolet light. This method is used to detect very small leaks that cannot be found with the halogen leak detector. Fluorescent dyes are injected into the system using a special injection tool. The dyes may also be placed directly into a newly replaced system component. Different dyes are used on the R-one-thirty-four-A and the R- twelve systems. Figure 9-3, J Leak Test Dye Injector for R 134A System Note: The dyes will indicate leaks by glowing yellow-green under ultraviolet light. 9-9

10 GM vehicles built after November two thousand one have leak detection dye in their systems right from the factory. Figure 9-4, Because not all tracer dyes are compatible with the GM-specific type of pag oil, GM recommends that only tracer dye J be used on R-134- A systems. Tracer dyes are also available for use on the R-twelve systems. Additional required tools include an ultraviolet light and fluorescence enhancing glasses, refrigeration leak detection notice labels, and dye injectors. Separate injectors are used for R-134-A and R

11 Some guidelines to keep in mind when using fluorescent tracer dyes on General Motors systems are: Use only a quarter ounce of dye. This is the amount needed to detect leaks. Increasing the amount will not shorten the time for leak detection; it would most likely cause system reliability concerns. Complete the refrigerant leak detection notice label supplied if you use the dye. This label notifies other service technicians that a tracer dye may still be in the system. Use of the R-one-thirty-four-A tracer dye requires time. Depending on the leak rate, it may take as little as 15 minutes or even up to 7 days for the leak to become visible under the black light. Tracer dye, mixed with pag oil, is retained in the system and may be detected for more than two years. Pag oil is water soluble, and traces of pag oil found at leaking joints can be "washed out" by condensation on refrigerant lines or the evaporator core. This can make some leaks harder to find using a dye detector. Fluorescence at the drain opening would indicate a core leak. After using the dye, wipe all repaired leaks or component access ports with General Motors solvent number to prevent a possible false diagnosis at a later time. 9-11

12 Lesson 1 Review Questions: 1. Halogen leak detectors. a. should not be used where fuel vapors are present b. use tracer dyes to find leaks c. are used to check for leaks on the top side of fittings d. detect only R-134a leaks 2. Tracer dye may take up to days to indicate a leak. a. 7 b. 10 c. 30 d The three settings on the J39400 halogen leak detector. a. change the sensitivity of the detector b. have no affect on the detector c. select the refrigerant to be detected d. change the type of alarm 9-12

13 Lesson 2: ACR 2000 Familiarization Welcome to the ACR2000 familiarization. The goal of this course is to provide you with the ability to maintain the ACR2000 and use it to diagnose and repair vehicles. Objectives The information and activities, when applied, from this lesson will enable you to: Identify the correct operation of the ACR2000 Identify differences between the ACR4 and ACR2000 Identify ACR2000 maintenance and upkeep Identify Service and Diagnostic Procedure using the ACR2000 Tasks and Competencies NATEF Area VI. A. 1. Identify and interpret heating and air conditioning concern; determine necessary action 2. Research applicable vehicle and service information, such as heating and air conditioning system operation, vehicle service history, service precautions, and technical service bulletins. 3. Locate and interpret vehicle and major component identification numbers (VIN, vehicle certification labels, calibration decals). 4. Performance test A/C system; diagnose A/C system malfunctions using principles of refrigeration. 5. Identify refrigerant type; conduct a performance test of the A/C system; determine necessary action. 6. Inspect the condition of discharged oil; determine necessary action 7. Determine recommended oil for system application. 8. Perform correct use and maintenance of refrigerant handling equipment. 9. Identify (by label application or use of a refrigerant identifier) and recover A/C system refrigerant. 10. Recycle refrigerant. 11. Label and store refrigerant. 12. Test recycled refrigerant for non-condensable gases. 13. Evacuate and charge A/C system. 9-13

14 STC Tasks: 1. Identify safety procedures to be followed when working with refrigerant systems and refrigeration systems 2. Describe the proper use of A/C service equipment utilizing approved service procedures 3. Describe approved HVAC servicing procedures 4. Describe refrigerant leak detection procedures 5. Describe refrigerant leak detection using dyes 6. Describe refrigerant leak detection using electronic leak detectors 7. Describe the impact of refrigerants on the environment 8. Identify the laws and regulations regarding approved handling of refrigerants 9. Identify system pressures using the ACR Compare System pressures to diagnostic tables 11. Identify the causes of abnormal system pressures using the pressure zone graph and diagnostic tables 12. Select the correct repair procedure in response to the pressure zone graph and diagnostic table 13. Recover refrigerant from a vehicle A/C system (ACR 2000) Evacuate a vehicle A/C system Recharge a vehicle A/C system Perform a performance test on a vehicle's A/C system Leak check an A/C system (electronic detector) Leak check an A/C system (trace dye/uv light) 9-14

15 Outline Discuss the following agenda items Introduction Lesson 2A: Explain Causes of A/C service dissatisfaction Lesson 2B: Describe New features of the ACR 2000 Lesson 2C: ACR 2000 maintenance and upkeep Lesson 2D: ACR 2000 Diagnosis and Service Summary / Post-Test Strategy Based Diagnosis Introduce strategy based diagnostics Explain that you will present material using this procedure: Step 1. Verify customer concern Step 2. Make Quick checks Step 3. Follow diagnostic system checks Step 4. Check bulletins Step 5. Diagnostics Step 6. Decision on cause isolation Step 7. Repair and verification 9-15

16 Lesson 2A: Causes of A/C Service Dissatisfaction In Lesson 2A we want to introduce the following objectives: Describe air trapped in a vehicle's A/C system Explain inaccurate charging levels First we will look at air trapped in the system. Air Trapped in the System When dealers were surveyed across the country, it was discovered that many dealers had unacceptable levels of air in the ACR 4 recovery tank. Under normal operating conditions, the ACR 4 will purge the air in the recovery tank. Survey Findings It was discovered that the evacuation cycle was being cut short by some technicians. This defeats the air purge process. The air purge function is tied to the preset 15 minute evacuation cycle. Buildup of air in the recycled refrigerant occurs when the time period is cut short. As a result, vehicles recharged with refrigerant containing air perform poorly. During high ambient temperatures, systems with more than 2% air will have a noticeable performance decrease Charge Accuracy When the ACR4 was introduced in 1993, most vehicle A/C system refrigerant capacities were in the 3 to 4 pound range. The ACR 4 accuracy range is +/- 6oz and is dependent on the technician to closely follow the charging procedure. Refrigerant capacities for today's cars average 2.0 pounds and GM sells some cars with capacities as low as 0.75 pounds Let's look at a table that shows how charge error becomes excessive as A/C system charge capacities have become smaller. Charge Accuracy Slide The ACR 2000 uses a highly accurate system that charges at +/- 1oz. A/C system performance is dependent on the proper charge in the vehicle This level of charge accuracy ensures consistent system performance 9-16

17 Charge Accuracy Charge +/- +/- +/- 1oz. 4.0 lbs. system 9% 3% 1.50% 3.0 lbs. system 13% 4% 2% 2.0 lbs. system 19% 6% 3%.75 lbs. system 50% 17% 8% Review Question 1: What is the ACR 2000's charge accuracy? 9-17

18 Lesson 2B: New features of the ACR2000 Upon completing this lesson you will be able to: Explain how built-in refrigerant identifier checks for contamination prior to recovery Explain automatic refill Explain time-saving features Explain automatic air purge Identify automatic oil drain function Identify operational features First we will discuss the operational features of the ACR

19 ACR2000 Operational Features Figure 9-6, ACR200 Front View Component locations and identifiers on ACR2000 ACR2000 control panel Main power switch Up-down keys Numeric keys Function keys Display Low side gauge High side gauge Red light on top of unit Filter identifier 9-19

20 Component Location Rear View View component locations and identifiers on ACR2000 rear view Connections for temperature/air velocity probes Circuit breaker RS232 serial data connector (phone port) Figure 9-7, ACR2000 Rear View 9-20

21 Component Locations Side View Source tank (disposable, inverted) Black hose for connection to source tank Tank strap to secure tank Field service couplers (color coded) Oil drain bottle Optional air flow connector Review Question 2: How many temperature probes are used on the ACR2000? Oil Drain Bottle Figure 9-8, Oil Drain Bottle 9-21

22 Component Locations Inside Rear View Compressor oil separator System oil separator Filter-Drier, replace when display shows "Change Filter" Compressor Manifold block solenoid assembly Figure 9-9, Component Location Inside Rear View 9-22

23 ACR2000 Function Overview Function Keys Overview Let's look at some example menus on the ACR2000 The function keys change depending on the service operation and the unit's status The display shows five labels along the bottom with arrows pointing to the function keys below To make a selection, press the function key immediately below the label/arrow All five keys are not always active; follow labels on the display Figure 9-10, ACR2000 Display Menu 9-23

24 Numerical Keys Using the numerical keys we can enter Evacuation time Vacuum level Recharge weight (if it is different from the default amount shown on the display The number keys are also used to enter your shop elevation above sea level. Contact your local airport or got to This web-site address can also be found on page 10 of the operator's manual. Figure 9-11, ACR2000 Numerical Keys Up/Down Arrow Keys Messages are shown in the display to indicate options or required actions 9-24

25 Figure 9-12, ACR2000 Menu Using Arrow Keys Review Question 3: When diagnosing or documenting a vehicle, it is best to keep the ACR2000 in what mode? 1. Snapshot 3. Flush 2. Evacuation 4. Vacuum Pressure Gauges Gauge Function High and low side pressure gauges are equipped with red "follower" needles to show maximum and minimum pressures Pressures are shown on the high and low side gauges and on the display, and other operating information is shown on the display The follower is carried with the pressure gauge needle to the highest or lowest operating pressure and stays there when the regular needle indicates other pressures Figure 9-13, ACR2000 Pressure Gauges 9-25

26 Lesson 2C: ACR2000 Maintenance and Upkeep Upon completion of this lesson you will be able to: Identify simple set-up Initial General Identify operator tips Detail circuit protection Explain source tank replacement Describe replacing identifier filter Describe general maintenance ACR2000 Initial Set-Up It's a good idea to leak check your hook-up You need to set up the ACR 2000 for the elevation of your dealership Press start to begin the internal evacuation of air from the tank and automatic fill of the internal vessel It takes about minutes to pre-charge internal vessel with 12 pounds of R-134a refrigerant Keep track of refrigerant usage through refrigerant management screen General set-up for the ACR2000 Remove from Box Accessory Box at Rear Plug in Power Cord Self-Diagnosis Mode Initial Set-Up Mode Default Language Measurement Units Facility Elevation Date/Time Attach Low and High Side Hoses Attach Red and Blue Temperature Probes Install Disposable Source Tank Secure Tank 9-26

27 "Start" Internal Evacuation of air Pre-Charge internal vessel Automatic Purge Mechanism on internal vessel Refrigerant Management Screen tracks refrigerant usage Other preferences available at set up menu To adjust the contrast on the display, press ENTER when CONTRAST is highlighted, then use UP and DOWN keys to adjust to the desired contrast. Once a vehicle has been serviced with the ACR2000, you can access a record of the weight of refrigerant passed through the filter-drier These preferences are available at any time ACR2000 Start Operation Turn on main power switch There will be a 0:45 second delay The menu display shows main menu and select operation when unit is ready for operation Review Question 4: It takes about minutes to pre-charge the internal vessel with 12 pounds of 123A refrigerant. True False 9-27

28 Circuit Protection Locations On Top View There are two circuit breakers on the back of the unit If either circuit breaker trips, all power to the unit is lost Press the circuit breaker button to reset Figure 9-14, ACR2000 Circuit Protection Replacing The Source Tank Why/When To Replace Source Tank Periodically the source tank on the back of the unity will run out of refrigerant The internal vessel contains enough refrigerant for several jobs, but it is important to replace the tank soon so that you don't deplete the refrigerant supply in the internal vessel 9-28

29 Replacing Source Tank Check Source Tank Do Not Deplete Refrigerant Release Tank Strap Close Source Tank Valve Connect Black Tank Hose and Open Valve Install New Disposable Tank Main Menu/can scroll menu and choose Tank Refill Replacing the Identifier filter Caution With Replacing Identifier Filter Notice: Visually inspect the identifier filter every day. If it begins to turn red, replace it immediately You run the risk of damaging the identifier if the filter isn't replaced Review Question 5: If the identifier filter turns black it needs to be replaced. True False General Maintenance Preventive Maintenance 1. Wipe off the unit with a clean cloth to remove grease, dust and other dirt. 2. Periodically check the internal components for leaks. Over time, fittings can be loosened as the unit is moved. Turn OFF the unit Disconnect it from the power source Open the rear of the unit and trace the lines with a leak detector Check connections on the back of the unit. Tighten any loose fittings or connections you may find. 9-29

30 Review Exercise In this exercise you need to match the control component 9-30

31 Lesson 2D: ACR2000 Diagnosis and Service The ACR2000 is designed for all refrigerant related vehicle A/C service requirements. Upon completion of this lesson you will be able to: Describe vehicle hook-up Explain recovery/recharge Identify Snapshot menu Identify Flushing process Identify Zone diagnostics Perform Diagnostic exercise A/C System Performance Test Vehicle Hook-up Proper Safety Precautions Always wear eye protection and protective clothing when working with refrigerants Be sure the vehicle is in Park and service hoses are clear of moving components before starting the engine Provide adequate ventilation. Vehicle exhaust fumes can cause injury or death Reminders Always close the coupler valves before disconnecting the hoses from the vehicle. Snapshot display on the ACR2000 allows you to capture and print vehicle operating information Next we are going to discuss recovery/recharge from the vehicle. These are the steps to correctly hook-up a vehicle. Select Snapshot Mode Connect Red High-Side Hose Connect Blue Low-Side Hose Place Red Temperature Probe in Center Outlet Place Blue Probe at Condenser Start Engine and Run A/C System Check System Pressures Snapshot Display Feature / Recovery / Exit 9-31

32 Recovery Procedures Refrigerant Recovery Typical recovery Select recover mode Connect red high-side and blue low-side hoses Ensure coupler valves are open Ensure oil catch bottle is empty Press start to begin recovery If low system pressure message is detected, perform leak checks When recovery completes the unit will stop automatically Red indicator light flashes and unit beeps Display shows recover complete System oil is drained into oil catch bottle Measure removed oil Dispose old oil and replace oil drain bottle The ACR2000 automatically restarts to recover any additional refrigerant remaining in system Recap of Process When all refrigerant is recovered, and the A/C system has been pulled into a vacuum, the unit will stop automatically The ACR2000 will also clear all refrigerant from its hoses and internal components When this is done three things occur Red indicator light flashes Display shows recover complete System oil is automatically drained into the oil catch bottle 9-32

33 Review Question 6: The system oil is automatically drained into the catch bottle: a. After recovery is complete b. After recharge is complete c. After Vacuum is complete d. After flushing is complete Pulling a Vacuum Before recharging a vehicle, you must pull a vacuum to remove air from the system. Note: Altitude can affect the unit's ability to pull a vacuum This is why correctly setting the altitude during initial set-up is so important Remove any air from system Connect hoses Select vacuum Use arrow key for longer evacuation time Press start to accept the displayed time period Unit will run until it reaches 28 inches mercury Correctly setting the altitude in initial set-up is important to correctly pull a vacuum Charging the Vehicle The ACR2000 has a default charge amount of 2 pounds. However, the default can be reprogrammed for other weights. You must pull a good vacuum before charging The ACR2000 will charge through the HIGH side, unless you select the low side Do not jar or disturb the unit in any way during charging 9-33

34 Note on charging a vehicle Two points must be stressed before reviewing vehicle charging Complete evacuation is essential Default charge weight is 2.0 lbs. Connect hoses and open service couplers Select charge function Options Next for 2 lb. Default Units to change unit of measurement Unit will charge through high side unless low side is chosen Press next to enter selections Press start to begin charging or Press back to change settings Do not disturb or jar unit once charging begins Recovering Hoses After charging process is complete and you have finished your snapshot, the display prompts you to recover hoses. It is important that refrigerant in the hoses is removed or it may cause incorrect measurements for the next vehicle serviced If you leave hoses connected to vehicle, the vehicle will be needlessly recovered a second time Note for recovering refrigerant from the hoses ACR2000 switches to snapshot once charging is complete This snapshot mode allows performance check on repair and a printout with warranty code Snapshot prompts to recover the hoses Close both valves and remove hoses from vehicle If hoses are left connected vehicle will be recovered a 2nd time needlessly Press start to begin hose recovery This removes excess refrigerant from hoses It must be removed from hoses to allow accurate measurements for next vehicle 9-34

35 Review Question 7: What is one thing you should NOT do when the ACR2000 is charging? Snapshot Data To assure that the vehicle's A/C system is operating properly, you should run it and capture another snapshot. Press main menu, then select snapshot Press start Start the vehicle and let it run until it reaches operating temperatures and pressures Then press print to get a copy of the performance data and the encrypted code If A/C system operation is satisfactory, turn off the engine Close the service couplers on the high side and low side hoses Disconnect the hoses from the vehicle's access ports Press done so you can: Clear hoses Avoid recovering car Review Question 8: What should be done to check that a system is operating properly? a. Let the vehicle sit over night? b. Perform snapshot data? c. Perform a leak check? d. None of the above? Figure 9-16, Snapshot Data 9-35

36 Flushing Process Flushing, like all other processes, is easy with the ACR2000. Things to remember Flushing is determined by tank pressure Not pump run time After flushing Refrigerant is processed by the ACR2000 Filtered by the recovery recycling circuit Returning it to SAE purification levels ACR2000 ensures the R134A available for customer vehicles is 99% pure Various adapters are available to accommodate the variety of compressors Using ACR2000 as part of new A/C system performance test Factors measured by ACR2000 Ambient air temperature Ambient air humidity High side pressure Low-side pressure Discharge temperatures (two temp probes) 9-36

37 Zone Diagnostics The first part of the performance test checks system operation and compares high and low side pressures. Based on the pressures, you are sent to a "Zone" diagnostic procedure. Pressure Zone Chart Pressure Zone A: Suggests improper air delivery An undercharged system System contaminants Pressure Zone B: Identifies improper compressor operation Under-charged system Pressure Zone C: Restriction at the condenser Malfunction at the expansion device Possible air mixed in the refrigerant System over charged Pressure Zone D: Restriction in refrigerant system 9-37

38 Diagnostic Exercise Diagnostic Scenario Let's see how the ACR2000 functions during diagnosis of a typical A/C service scenario, initiated by customer concern. Review important steps before starting A/C System Performance Test: Ambient temperature at least 16ºC (60ºF) Do not induce additional air flow across the vehicle during the test If sent to this test from a DTC diagnostic table, clear the DTC upon completion Now let's go to the first step in our diagnostic exercise. 9-38

39 Customer Concern: A/C system isn't cool enough on a Buick LeSabre. Your visual inspection shows nothing unusual. A/C Performance Test Step 1 Note the ambient temperature displayed on the ACR2000. Both the pressures and ambient temperature are in the 70's. Figure 9-19, Ambient Temperature Let's move on in our diagnostic exercise. 9-39

40 Note: Determine is refrigerant is adequate Allow A/C system to equalize for 2 minutes Hook up ACR2000 as previously shown Note the ambient temperature Note the readings for low and high side STATIC pressure Review Question 9: Using your chart on page 38 answer the following question on the video we just watched: Are these readings what we should expect? Based on that response answer the following question. Review Question 10: What do we do next? a. Continue to step 2 b. Leak check the system c. Go to symptom-based diagnostics d. Return vehicle to customer, no trouble found 9-40

41 A/C Performance Test Step #2 This test examines basic system output Open the driver window 5 to 6 with other windows shut Set A/C MAX Put blower to highest position Set temperature control to coldest position With A/C outlets open, install ACR2000 temperature probes into the left and right center A/C air outlets Apply parking brake and put transmission in park Start and allow engine to idle for 5 minutes Record ambient temperature and relative humidity at the time of testing Check for frost areas indicating a restriction the lines Listen for unusual noises such as compressor or belts Record system output parameters / RESET to update data and printout outlet air temperature, low side pressure and high side pressure Compare low and high side pressures and the outlet temperatures to the table and graph in Service Information 9-41

42 Using the table on page 38 answer the following question on the video we just watched. Review Question 11: Are these readings within the specified ranges? Review Question 12: What do we do next? a. Go to pressure zone A diagnostics b. Go to pressure zone B diagnostics c. Go to pressure zone C diagnostics d. Continue to step 3 A/C Performance Test Step 3 Step 3 makes sure the system has a fair chance to stabilize Compare the low and high side pressures as well as the output temperature on the table Note: A/C Performance Test Step #3 This test allows for various vehicle differences Let system operate additional 5 minutes, reset and printout the pressures and temperatures again Compare the low and high side pressures and output temperatures to the table Using your table on page 38, answer the following question on the video we just watched. Review Question 13: Are the readings now within the specified ranges? Review Question 14: What do we do next? a. Go to pressure zone A diagnostics b. Go to pressure zone B diagnostics c. Go to pressure zone C diagnostics d. Go to pressure zone D diagnostics Pressure zone C diagnostics lead your conclusion to? 9-42

43 Summary The ACR2000 is a highly automated A/C service system Precise accuracy Easy vehicle interface and function control Snapshot printouts to document service/diagnostic procedures Always follow the SBD process Strategy Based Diagnositcs Step 1. Verify customer concern Step 2. Make quick checks Step 3. Follow diagnostic system checks Step 4. Check bulletins Step 5. Diagnostics Step 6. Decision on cause isolation Step 7. Repair and verification 9-43

44 Post Test 1. When experiencing high ambient temperatures, systems with more than air will have a noticeable performance decrease a. 6% b. 3% c. 2% d. 1% 2. The ACR2000 charge accuracy is at: a. +/- 1 0z. b. +/- 2 oz. c. +/- 3 oz. d. +/- 4 oz. 3. The ACR 2000 recycling ability ensures what percentage of pure R134a? a. 99% pure R134a b. 98% pure R134a c. 97% pure R134a d. 96% pure R134a 4. Refrigerant usage is tracked on the ACR2000 using the: a. Snapshot Scroll screen b. Recharge Management screen c. Vacuum usage screen d. Refrigerant Management screen 5. Visually inspect the identifier filter every day. If it begins to turn replace it immediately. a. Black b. Gray c. Red d. Cloudy 9-44

45 6. During initial set-up, the elevation of your service facility must be entered within feet. a. 100 b. 200 c. 300 d. 400 e The ACR2000 should be plugged in during business hours in order to: a. Always be calibrated and set-up b. Purge excess air from the internal vessel c. Clear the filter drier when not in use d. Keep air out of the connections and hoses 8. When the ACR2000 recovery procedure is complete: a. The red indicator light flashes b. The display shows Recover Complete c. The system oil is drained into the oil catch bottle d. All of the above 9. can affect the ACR2000's ability to pull a vacuum. a. Temperature b. Humidity c. Altitude d. Pressure e. None of the above 10.If all the refrigerant is not recovered from the hoses it may cause: a. The internal vessel to become over charged b. Incorrect measurements for the next vehicle recovered c. Incorrect snapshot data to be recorded d. A depletion of refrigerant in the internal vessel 9-45