9781284119244 Auto HVAC, Chapters 6 and 77

MASTER AUTOMOTIVE TECHNICIAN SERIES

SAMPLE CHAPTERS 6 and 7

Automotive Heating, Ventilation, and Air Conditioning

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Joseph Wagner Kirk VanGelder

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CONTENTS

Chapter 1

Strategy-Based Diagnostics

Chapter 2

History and Safety Procedures of Mobile HVAC Systems

Chapter 3

Operating Principles, Heat Transfer and Temperature/Pressure Relationship

Chapter 4

Refrigeration Cycle and Basic Component Operation

Chapter 5

Environmental and Legal Concerns and Responsibilities

Go to

Chapter 6

HVAC System Tools for System Repairs

Go to

Chapter 7

AC Refrigerant and Refrigerant Oil

Chapter 8

AC Compressor Design, Operation and Controls

Chapter 9

Restrictions, Accumulators and Driers

Chapter 10

Heat Exchangers, Hoses, Lines, Fittings and Seals

Chapter 11

AC System Inspection, Diagnosis and Repair

Chapter 12

AC System Recovery, Recycling, Evacuation and Recharge

Chapter 13

Thermal Management Systems and Components

Chapter 14

Thermal Management System Inspection, Diagnosis and Repair

Chapter 15

Air Distribution and Control System Operation

Chapter 16

Air Management and Control System Inspection, Diagnosis and Repair

Chapter 17

Emerging Mobile HVAC and Thermal Management Technology

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CHAPTER 6

HVAC System Tools for System Repairs Learning Objectives After reading this chapter, you will be able to: ■ ■ ■ ■

6-01 Describe the tools needed to test HVAC system performance.

6-02 explain the proper use of a refrigerant identifier.

6-03 Describe the purpose and need for sealant detectors.

6-04 Identify the tool used to test system pressure.

■

■

6-05 Identify refrigerant recovery, evacuation, and recharging tools.

6-06 Describe the different tools and methods used to detect system leaks.

You Are the Automotive Technician A customer brings in a vehicle they just purchased from an unknown private seller. The seller disclosed that the air conditioning was not working properly but was not aware why it wasn’t working. The customer said that they purchased and installed a recharge/leak sealant kit from a local auto parts store, but the system still is not operating correctly. The customer wants to leave the vehicle for a diagnostic check and repair estimate.

1. What tools will be needed to diagnose the system?

2. How will you know whether sealant has been installed into the HVAC (heating, ventilation, and air conditioning) refrigerant system?

Will the sealant cause any damage to the shop equipment if installed on this vehicle?

3. If there is a leak, what tools will be needed to locate the leak?

4. What components will need to be serviced or replaced?

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Chapter 6 HVAC System Tools for System Repairs

▶▶ System 6-01 Describe the tools needed to test HVAC system performance.

Performance Testing Tools

Understanding the proper use of specialized tools will allow the technician to begin to ­perform basic service and diagnostic system tests on a mobile HVAC system. When ­performing a diagnosis or servicing a pressurized cooling system or refrigerant system, there is always the possibility of bodily harm, so all safety precautions must be followed.

Please note that the tools shown in this chapter are general in illustration. To ensure proper use and to avoid any damage or bodily injury, the technician should always follow the ­manufacturer’s operating manual specific to each tool.

Thermometers A commonly used tool for diagnosing HVAC systems is the thermometer. There are two types of thermometers used: mechanical and electronic. The most common is ▶▶FAST FACT the ­pocket-style, dial-faced thermometer (FIGURE 6-1). There is also a digital version Some technicians refer to the non-­ ­(FIGURE 6-2). These thermometers are generally used to measure air temperature and are either installed into a dash vent or left out in the open. contact thermometer as a laser thermometer. This is incorrect, because the Another type of thermometer is the probe type, commonly used with digital multimelaser is used only to pinpoint the spot ters. The tip of the probe must be placed in the air to be measured or held directly against where the temperature is taken.The laser the component being measured (FIGURE 6-3). has no function in the measuring of the An infrared, non-contact-type thermometer (FIGURE 6-4) quickly calculates the temtemperature. perature by measuring the amount of infrared energy released by an object. A non-­contact thermometer cannot measure the temperature of air. While squeezing the trigger, a laser is projected at the object to pinpoint the area to be measured. Note that when measuring, certain objects might be too reflective (such as an unpainted condenser or refrigerant line) and cause an incorrect reading. A technician should wrap black electrical tape around or color the area with a dark-colored marker to get a correct reading. The distance from which a measurement is taken can also affect the temperature reading. Refer to manufacturer’s instructions for specific details.

The four-channel temperature probe is a kit capable of measuring the temperatures of four different areas at the same time (FIGURE 6-5). The kit may come with an air probe (FIGURE 6-6) and clamp probes for attaching to metal lines (FIGURE 6-7). The probe is also capable of calculating the different temperatures of each other. This is important for determining component efficiency when a technician is testing performance. This test will be covered in more detail in Chapter 7.

FIGURE 6-1 Dial-type pocket thermometer.

FIGURE 6-2 Digital-type pocket thermometer.

FIGURE 6-3 Digital multimeter with temperature probe.

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Refrigerant Identifiers

FIGURE 6-4 An infrared, non-contact-type thermometer.

FIGURE 6-5 Digital multimeter with temperature probe.

FIGURE 6-6 Air probe.

FIGURE 6-7 Clamp probe.

▶▶ Refrigerant

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Identifiers

Before any service equipment is attached to any refrigerant system, it needs to be tested for content with a refrigerant identifier/analyzer (FIGURE 6-8). The analyzer will identify what type of refrigerant is installed, the level of purity (or contamination), and the amount of air in a system or container. The use of a refrigerant analyzer is not required, but it is highly recommended, because there is always the possibility of an unapproved refrigerant

6-02 Explain the proper use of a refrigerant identifier.

▶▶FAST FACT

FIGURE 6-8 Refrigerant

identifier or analyzer.

It is recommended to test all new cans, storage containers, and every vehicle for the type and quality of refrigerant.

Counterfeit or mislabeled refrigerants have been reported in the marketplace, and testing will ensure the quality of the refrigerant being installed in shop equipment and vehicles. Contaminated or counterfeit refrigerant must be stored and disposed of separately and can be quite expensive.

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Chapter 6 HVAC System Tools for System Repairs

or substance being installed in a vehicle. These unapproved chemicals can cause serious damage to equipment, which would require overhaul or replacement. Some models of ­identifiers come with adapters for the different types of refrigerant ­systems being tested.

▶▶ Refrigerant

Detectors

FIGURE 6-9 Refrigerant system sealant detector.

6-03 Describe the purpose and need for sealant detectors.

6-04 Identify the tool used to test system pressure.

System Sealant

The aftermarket industry has been providing vehicle owners many “quick fix” additives to install in their vehicles to repair leaks and make the HVAC system function again. Some of these fixes contain a sealant to stop small leaks. Some of the sealants in the aftermarket can have adverse effects on HVAC recovery/recycling equipment that may require either a complete overhaul or complete replacement. The use of a sealant detector will protect the investment in approved equipment (FIGURE 6-9).

▶▶ Refrigerant

System Pressure Tools

The most common repair in the HVAC system is refrigerant system charging. In order to determine whether the system is operating properly, a pressure reading must be taken from both the low side and the high side of the system. This will aid the technician in diagnosing the system as either undercharged or overcharged, or whether there’s a problem with one of the system components. These pressure-reading tools are referred to as pressure gauges.

Manifold Pressure Gauges

▶▶FAST FACT Before a manifold gauge is installed on a vehicle, both hand wheel valves should be closed. The valves should remain closed when the vehicle is running. If a digital manifold gauge set is being used, be sure to follow the manufacturer’s instructions on how to zero the gauge readings.

6-05 Identify refrigerant recovery, evacuation, and recharging tools.

The manifold gauge set is the most familiar tool for HVAC repair (FIGURE 6-10). The manifold gauge set allows the technician to perform pressure readings. A manifold gauge will allow a technician to perform functions such as recovering, evacuating, vacuuming, and recharging the refrigerant system. The gauge set is equipped with colored hoses and quick disconnect fittings. Notice the differences between the two sides. On the left of the manifold is the low side (blue), which displays vacuum (30’ Hg) and pressure (from 0 to 150 psi). On the right of the manifold is the high side (red), which displays pressure (0–500 psi). The middle auxiliary port (and the yellow hose) is used to charge and vacuum the refrigerant system. For specific details of the standard manifold gauge, refer to FIGURE 6-11. The quick disconnect fittings used to install the gauges for R-134a are shown in FIGURE 6-12. When performing pressure tests and system diagnostics, a digital version of the manifold gauge set is also available to be used (FIGURE 6-13).

▶▶ Refrigerant

Tools

System Servicing

After the technician has tested system performance and identified the system issue, the remaining refrigerant must be safely removed from the vehicle. Repairs are then performed, and the system is put into a vacuum. After passing a vacuum leak test, the system is properly recharged to vehicle specifications. Proper tool use is needed to perform an accurate, safe repair.

Recovery, Recycling, and Recharging Machines FIGURE 6-10 R-134a refrigerant manifold gauge set.

Any time the air conditioning system needs to be opened up for service, the refrigerant must be removed so that refrigerant

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Refrigerant System Servicing Tools

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▶▶FAST FACT High Side (Red)

Low Side (Blue)

Low Side Blue Hand Valve

Calibration Screws

Low Side Hose Hanger

High Side Red Hand Valve High Side Hose Hanger

The amount of refrigerant removed will gives an insight into the condition of the vehicle’s air conditioning system.

Compare the weight removed to the ­ under-the-hood sticker amount or current technical bulletin. If the amount recovered is less than specified, there is likely a leak in the system (undercharged).

If there is more than specified (overcharged), then someone else has likely worked on the system, and so a proper inspection is required. If it had the correct amount of refrigerant, then the system most likely has no leaks and a different diagnosis should be performed.

Low Side Hose & Service Port Auxiliary Hose & Service Port High Side Hose & Service Port

FIGURE 6-11 R-134a refrigerant manifold gauge set.

FIGURE 6-12 R-134a refrigerant quick connect fittings.

will not be released into the atmosphere. Removing refrigerant is called reclaiming or recovering. It is then filtered or recycled to be used in system recharging. This process is commonly performed by an R/R/R machine (a recovery, recycling, and recharging machine) (FIGURE 6-14). The recovery process uses the R/R/R machine to remove refrigerant from the system. The air conditioning R/R/R machine is equipped with pressure gauges, a vacuum pump, an internal refrigerant storage tank, and a recharging scale. This allows one machine to perform all of the functions of refrigerant system repairs. Newer R/R/R machines now have the ability to be programmed to simultaneously recover, evacuate the system to desired vacuum readings and/or time, check perform the system for leaks, and then recharge the system with the proper oil and refrigerant. This newer machine allows the technician to perform other repairs while the automated process is running.

FIGURE 6-13 R-134a digital refrigerant manifold gauge set.

FIGURE 6-14 An R/R/R machine.

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Chapter 6 HVAC System Tools for System Repairs

FIGURE 6-15 Electric vacuum pump.

FIGURE 6-16 Air pressure vacuum pump.

Vacuum Pumps

▶▶FAST FACT It is important to perform regular vacuum pump maintenance on equipment. After a certain amount of time and operation, vacuum pump operation will diminish and service will take longer. Pump wear will also occur. Be sure to properly dispose of used vacuum pump oil: it is considered hazardous waste and cannot be disposed with regular engine oil waste.

▶▶FAST FACT If the micron does not hit 1,000 microns within the total vacuum time, then spin the clutch of the compressor and watch the pressure gauge. If the pressure rises, then the clutch seal is faulty.

6-06 Describe the different tools and methods used to detect system leaks.

Once repairs have been made on a mobile HVAC system, the last step prior to recharging it is to put the entire system into a vacuum. Not only does a steady reading of vacuum after the pump has shut off show system integrity, but it also removes moisture. As discussed in Chapter 2, different chemicals (such as water) boil at different temperatures, depending on pressure. By putting the refrigerant system into a vacuum, any moisture in the system is boiled off and removed from the system. There are two common types of ­vacuum pumps: electric (FIGURE 6-15) and air pressure pumps (FIGURE 6-16). Most recovery and recycling machines are equipped with an electric pump.

Micron Gauge The micron gauge (FIGURE 6-17) is used to precisely measure vacuum. Where a vacuum gauge will have markings at 29" then 30" of vacuum, the micron gauge can measure accurately between 29" and 30" to determine exactly how well the system is being evacuated. With the micron gauge, the pressure is measured in microns, or one-thousandths of 1 ­millimeter. To put it in perspective, in 1 inch, there are 25,400 microns. So, 0 microns equals a perfect vacuum (roughly 30" Hg), and 25,400 microns equals approximately 29" Hg. This super-fine measurement of vacuum allows technicians to read accurately enough to ensure that all of the moisture has been removed from the air conditioning system. It is recommended that a refrigerant system be evacuated for 30 to 45 minutes at the minimum until a micron reading below 1,000 is achieved. The ideal reading should be below 600 microns.

Oil Injector During certain system repairs, oil may need to be added to the system. This is done after the evacuation process is completed, when the system cannot be reopened. An oil injector (FIGURE 6-18) allows for the addition of oil or dye into the system. Atmospheric pressure or physical force is used to install oil into the system through the low-side service port.

▶▶ System

FIGURE 6-17 Vacuum

FIGURE 6-18 An oil

micron gauge.

injector.

Leak Detection Tools

The air conditioning system is a sealed system that must not leak; however, leaks do occur and are a common reason that the air conditioning system is not working properly. Leak testing should be performed on every air conditioning system that is low on refrigerant or has just been repaired. Leak testing can be done by using any one of several methods: e­ lectronic leak detectors, dye testing, or nitrogen testing.

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System Leak Detection Tools

FIGURE 6-19 Ultrasonic leak detector.

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FIGURE 6-20 Heated diode leak detector (with ultraviolet

detecting light).

Electronic Leak Detectors Types of electronic leak detectors include ultrasonic, heated diode, and corona suppression. Ultrasonic leak detectors (FIGURE 6-19) are supersensitive microphones that can pick up the hiss of a leak that is too small to be heard by human ears. Heated diode leak detectors (FIGURE 6-20) use electricity to determine whether there is a leak. R-134a passing by the diode is broken down, thereby creating an electrical current charge; the internal mechanics of the diode use this charge to determine how much refrigerant has passed. The diode beeps or chirps at increasing rates as the rate of refrigerant increases.

The heated diodes are considered the best and most common leak detectors for R-134a refrigerant systems. Corona-suppression leak detectors (FIGURE 6-21) function in much the same way as the heated diode, except that any particle passing through the device, including dust, will set it off. With corona-suppression, refrigerant gas is used as an insulator to slow current between electrodes. All of the electronic detectors require that the air conditioning system have a charge of refrigerant for the leak detector to detect a leak.

A leak is located by watching the detector lights and listening to the sounds. Starting with the sensitivity on a high setting and turning down the sensitivity as the alarms and lights get louder and brighter will help pinpoint the problem. Moving with a steady hand and being patient are critical to using this device. When using the sniffer, be sure there is no wind or draft on the vehicle.

▶▶FAST FACT It is important to note that refrigerant is heavier than air. When using an electronic leak detector (or sniffer), be sure to test underneath the component being tested.

This will allow the strongest sample available to be detected. All electronic leak detectors should meet Society of Automotive Engineers (SAE) Standard J2913.

J2913 equipment must detect a leak as small as 0.015 ounces over the course of a year.

▶▶FAST FACT Injecting refrigerant oil or concentrated dye should always be installed into the low side of the air conditioning system with the vehicle off.

Refrigerant Dye, UV Light, and Dye-Enhancing Goggles Using ultraviolet (UV) light and refrigerant dye is a common way to test for leaks in an air conditioning system. Some vehicle manufacturers add dye during the ­manufacturing process. When using dye for the first time on an air conditioning system, the dye has to be injected as a concentrate into the system. Some machines have a special port for ­injecting the dye; in other machines, it can be injected using a dye injector ­(FIGURE 6-22).

After installing the dye, the air conditioning system must be operated so that the dye is distributed throughout the system. To locate the leak, a UV light is required. When using a UV light, make sure all safety precautions are followed, including wearing UV dye-enhancing safety glasses.

Nitrogen Nitrogen testing has been used in the home and transport refrigeration repair industry for a long time, but it is not as common in the automotive industry. Nitrogen is a safe gas that can be used for testing discharged systems or for prechecking for a leak after repairs have been made and before recharging the system. Nitrogen testing requires a nitrogen tank, ­pressure regulator, adapters (FIGURE 6-23), and a microleak detector solution (­FIGURE 6-24). Soapy water is not recommended, because of its corrosive

FIGURE 6-21 Corona-suppression leak

detector.

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Chapter 6 HVAC System Tools for System Repairs

FIGURE 6-22 UV dye injector kit with dye-enhancing goggles.

FIGURE 6-23 A nitrogen leak-detecting kit with

regulator and adapters.

properties and inability to show m ­ icroleaks. The nitrogen is used to simulate working conditions of the air conditioning system and provides enough force to find any high-pressure leaks. Whereas electronic leak detectors and dye leak tests require that the air conditioning system be r­ elatively full of refrigerant, nitrogen testing requires an empty air conditioning system. If a nitrogen test is the method being used, first recover the air conditioning system. ▶▶FAST FACT

FIGURE 6-24 Microleak bubble solution.

Dry nitrogen is the only gas to be used in the air conditioning system for detecting leaks and removing traces of flushing chemicals from the system. Using any other propellant may cause harm and damage.

Dry nitrogen is an inert gas and will not explode or ignite like other gases, such as compressed air and oxygen.

▶▶Wrap-Up Ready for Review ▶▶ ▶▶

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▶▶

▶▶

▶▶

There are many specialized tools needed to properly diagnose and repair a mobile HVAC system.

The thermometer is used to measure temperature. They can either be an analog or a digital pocket type, a probe type, or a non-contact type.

A four-channel temperature probe can quickly determine temperature differences in four different locations. This style is important when testing system performance.

Refrigerant identifiers test for the type of refrigerant and level of purity. This could prevent possible equipment contamination and damage.

Refrigerant sealant detectors are useful to determine whether a sealant is present in a mobile HVAC system.

This could also prevent equipment contamination and damage.

There are different methods to determine refrigerant system pressures. The most common are analog pressure gauges, sometimes referred to as manifold gauges. The gauges are generally specific to a type of refrigerant and have that type of refrigerant service valves only on the hoses.

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▶▶

▶▶ ▶▶

An R/R/R machine is a common tool that recovers, recycles, and recharges a refrigerant system. The R/R/R machine typically also includes a set of pressure gauges and a vacuum pump.

R/R/R machines can also remove refrigerant oil. It is important to identify how much was removed from a system so that it can be reinstalled during recharging to maintain system oil capacity.

Vacuum pumps are used to lower the pressure in a refrigerant system, allowing water and moisture to boil off and prevent system problems with the water freezing.

A ­vacuum pump should run for a specified amount of time or until a specific vacuum reading is obtained.

Vacuum pumps must have regular oil changes to prolong pump life. The oil removed is considered hazardous waste and should be disposed of in a place separate from regular engine oil.

A micron gauge is used to determine a specific vacuum reading.

An oil injector is used to reinstall refrigerant oil or leak detection dye into the system without needing to open the system or repeat a vacuum.

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▶▶

Wrap-Up

There are many methods to perform leak detection.

They include dye and UV-enhancing light, an ultrasonic leak detector, a heated diode leak detector, a corona-­ suppression leak detector, and nitrogen charging with a leak detection microleak bubble solution.

Key Terms corona-suppression leak detector A leak detector where refrigerant gas is used as an insulator to slow current passing between two electrodes. dye-enhancing safety glasses Special safety glasses worn to prevent UV damage and enhance the appearance of U-indicating dye. dry nitrogen testing An inert gas used to leak test a refrigerant system under pressure. electronic leak detector A type of leak detectors that includes ultrasonic, heated diode, and corona suppression. four-channel temperature probe A testing device that is capable of measuring the temperatures of four different areas at the same time. heated diode leak detector A leak detector that uses electricity to determine whether there is a leak by breaking down refrigerant and changing an electrical current. infrared, non-contact-type thermometer A thermometer that quickly calculates the temperature by measuring the amount of infrared energy released by an object. manifold gauge A tool that allows a technician to perform functions such as recovering, evacuating, vacuuming, and recharging the refrigerant system. microleak detector solution A liquid spray that is used to determine the location of small leaks in a system by creating bubbles. micron gauge A device designed to measure vacuum very precisely. nitrogen An inert gas used for leak-testing a refrigerant system. oil injector A tool that allows for the addition of oil or dye into the system. probe-type thermometer A thermometer that directly measures the temperature of a surface. quick disconnect fittings Fittings that can quickly connect/ disconnect from a refrigerant system, with no refrigerant loss. reclaiming The process of removing refrigerant from a system and having it sent to a refrigerant reclaimer that returns the refrigerant to like new condition then sending out to be filtered and returned to like new condition. recovering The process of using the proper equipment to remove refrigerant from a system, filter it, and store it for future use. refrigerant analyzer A tool that can identify what type of refrigerant is installed, the level of purity (or contamination), and the amount of air in a system or container. refrigerant dye A dye used with a UV light to help find the location of a refrigerant system leak. refrigerant identifier Devices used to check for impurities in the air conditioning system.

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R/R/R machine A refrigerant recovery, recycle, and recharge machine. sealant A substance that, when it comes in contact with moisture, will slow a leak down. sealant detector A device used to test for the presence of sealant. thermometer Used to check the temperature of air exiting the heating ducts. ultrasonic leak detector An electric leak detector with supersensitive microphones that can pick up the hissing sound of a leak that is too small to be heard by human ears. ultraviolet (UV) light A light used with a special dye to indicate the location of a leak. vacuum pumps A device used to leak-test a system and lower the boiling point of water for easy removal.

Review Questions 1. Which of the following is not a tool used to measure temperature? a. A dial-type pocket thermometer. b. A probe-type thermometer. c. An anemometer. d. An infrared, non-contact-type thermometer.

2. Which of the following is not a refrigerant diagnostic tool? a. A refrigerant identifier. b. A sealant detector. c. A four-channel temperature probe. d. They are all commonly used today.

3. A refrigerant manifold gauge is equipped with all of the following except a. a high-pressure hose, fitting, and gauge that reads vacuum and pressure. b. a high-pressure hose, fitting, and gauge that reads pressure only. c. a low-pressure hose, fitting, and gauge that reads vacuum and pressure. d. an auxiliary port for refrigerant system vacuuming and recharging.

4. What function does an R/R/R machine not perform? a. Recycling. b. Removing. c. Recovering. d. Recharging.

5. What is the recommended amount of time and minimum micron reading that should be obtained to ensure the complete removal of moisture? a. 10 minutes, 10,000 microns. b. 30–45 minutes, 25,400. c. 30–45 minutes, below 600 microns. d. 10 minutes, 25,400 microns.

6. Which of the following are not considered an electronic leak detector? a. Ultrasonic. b. Heated diode. c. Corona suppression. d. Microleak bubble solution.

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Chapter 6 HVAC System Tools for System Repairs

7. A ______________ can test for “quick fixes,” which may cause equipment damage, that have been added to a refrigerant system. a. sealant detector b. refrigerant identifier/analyzer c. digital manifold gauge set d. four-channel temperature probe 8. A ______________ can test for unapproved refrigerant or substances that may cause equipment damage. a. sealant detector b. refrigerant identifier/analyzer c. digital manifold gauge set d. four-channel temperature probe 9. The amount of refrigerant recovered is recorded and ­compared to the specification. The system was found to have a charge of ½ capacity. What is most likely the problem? a. The system is overcharged with refrigerant. b. The system has been overcharged with oil. c. The refrigerant system has a leak. d. The wrong type of refrigerant was installed.

10. What tool is used to install oil into the system after a vacuum leak test has been performed? a. An oil injector. b. An R/R/R Machine. c. Both A and B. d. Neither A nor B.

ASE Technician A/Technician B Style Questions 1. Technician A says that a vacuum leak test is the last step before recharging a system. Technician B says that a system must be discharged before nitrogen testing. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 2. Technician A says it is OK to use regulated shop air to pressurize a refrigerant system to perform a leak test. ­ ­Technician B says that only dry nitrogen should be used to leak test a refrigerant system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 3. Technician A says that new containers of refrigerant should be tested before being installed into a vehicle or shop equipment. Technician B says that all vehicles should be tested for contaminated refrigerants before installing shop equipment. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 4. Technician A says that a non-contact thermometer uses a laser to pinpoint the area being tested. Technician B says that if the area being tested is too reflective, black tape or a dark marker should be used to get a correct reading. Who is correct?

a. Technician A b. Technician B c. Both A and B d. Neither A nor B 5. Technician A says that a refrigerant identifier should be used on a vehicle to prevent a possibly contaminated refrigerant from causing damage to shop equipment. ­Technician B says that sealant detectors should be used on a vehicle before causing damage to shop equipment. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 6. Technician A says that a manifold pressure gauge can read vacuum on the low-pressure side. Technician B says that a manifold pressure gauge can read vacuum on both the low-pressure and high-pressure side. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 7. Technician A says that an R/R/R machine will not recycle refrigerant. Technician B says that an R/R/R machine will not recharge refrigerant. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 8. Technician A says that used vacuum pump oil can be disposed of with regular used engine oil. Technician B says that any amount of refrigerant removed will help to determine whether there is a leak in the system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 9. Technician A says that a vacuum micron gauge can perform a very precise vacuum reading. Technician B says that a reading above 1,000 microns is an indication that all moisture has been removed from the system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 10. Technician A says that injecting oil into a refrigerant system will require the system to be put into a vacuum after the oil is injected. Technician B says that special glasses are not needed to find a leak when using UV dye. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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F F

H 2C F

F

CHAPTER 7

Air Conditioning Refrigerant and Refrigerant Oil

Learning Objectives After reading this chapter, you will be able to: ■

■

■

7-01 Identify the different types of refrigerant used in mobile HVAC systems.

7-02 Describe the procedure to test for sealants in a mobile HVAC system.

7-03 Describe the process for identifying refrigerants.

■

■

7-04 Explain counterfeit refrigerant and contaminated refrigerant disposal.

7-05 Identify the different types of refrigerant oils used in mobile HVAC systems.

You Are the Automotive Technician Another technician has asked you to get some refrigerant and refrigerant oil for the vehicle they are repairing.You contact the parts department and are asked what type and how much refrigerant and oil you need.

1.

2.

3.

4.

5.

6.

Why would the parts department ask you this?

Where could you obtain this information?

How many different types of refrigerant oil are there?

Do different refrigerants use different refrigerant oil?

What is the viscosity of the oil the vehicle requires?

If the vehicle is a hybrid, could it take different oil?

77

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Chapter 7 Air Conditioning Refrigerant and Refrigerant Oil

▶▶ Refrigerants 7-01 Identify the different types of refrigerant used in mobile HVAC systems.

▶▶FAST FACT While R-12 is no longer manufactured or imported into the United States, there is an inventory still available. As that inventory goes down, the price will increase.

Customers will then have to decide whether the cost justifies the use of R-12 or whether they want to retrofit their system to R-134a.

▶▶TECHNICIAN TIP Identifying refrigerants has become an important part of repairing air conditioning systems. The accidental mixing of refrigerants or the mixing of different types of refrigerant oil could damage the system and the machines that service air conditioners. Before recovering a system, the type of refrigerant in the vehicle must be identified to prevent the accidental contamination of the refrigerant in the recovering machine.

Cl

H C

Cl

F FIGURE 7-1 CFC R-12,

dichlorofluoromethane molecule.

F

F

F

C

C

F

H

One of the most vital components of the HVAC (heating, ventilation, and air conditioning) system is the refrigerant. The refrigerant in the mobile HVAC system is responsible for absorbing heat from and releasing heat to the vehicle. Refrigerant is defined as a stable chemical that is used to transfer heat while changing from a gas to a liquid in the condenser (releasing heat) and then back into a gas in the evaporator (absorbing heat) in the closed loop refrigerant circle of life. Refrigerant is generally a colorless and odorless substance with a very low boiling point. Although the use of refrigerant in mobile HVAC systems has not changed much, the type of refrigerant has mainly changed due to environmental and safety concerns.

Dichlorofluoromethane (CFC R-12), (R-12) Refrigerant The first common refrigerant used in mobile HVAC systems was referred to as R-12, or by the trade name Freon. The chemical name for R-12 is dichlorofluoromethane (CCL2F2).

R-12 is a member of the chlorofluorocarbon (CFC) family of gases (FIGURE 7-1).

R-12 was the first common refrigerant to be used in an automotive air conditioner. It is non­flammable, nontoxic, and stable at all temperatures; does not react with aluminum, steel, or copper; and is soluble in mineral oils. It has a boiling point of −21.8°F (−29.9°C). In the early 1990s, R-12 was found to be one of the leading causes of the depletion of the ozone layer, due to the element chlorine, a primary component of chlorofluorocarbon. CFCs have been banned by the U.S. government for use in refrigerants and from new vehicle installation after the 1994 vehicle year. Although R-12 will not be found in today’s production vehicles, technicians may still have customers with older vehicles that use R-12. As of 1996, R-12 is not allowed to be manufactured or imported into the United States.

Tetrafluoroethane (HFC R-134a) (R-134a) Once R-12 was identified as a substance that damages ozone, a new refrigerant was needed as an environmentally safe replacement. That refrigerant was R-134a, also referred to by the trade name Suva. The chemical name of R-134a is tetrafluoroethane (CF3CFH2). R-134a is in the hydrofluorocarbon (HFC) family of gases (FIGURE 7-2). R-134a is nonflammable and is accepted by the automotive world to be safe for automotive air conditioners. R-134a boils well below normal room temperatures and in the vaporizing process will absorb tremendous amounts of heat without increasing its own temperature. Although R-134a has a boiling point of −15.3°F (−26.3°C), which is nearly the same as R-12’s boiling point, R-134a is the only approved substitute for R-12 that can be retrofitted by following a specific procedure. Unfortunately, recent discoveries show that R-134a is a major contributor to greenhouse gases, so it also is being phased out of vehicle production around the world. R-134a will be completely phased out of new vehicle production by the year 2021.

One reason it is so important to always use the correct refrigerant is that polyalkylene glycol (PAG) oil mixed with mineral oil creates a hazardous gas that can corrode the air conditioning system. The mixture is considered a contaminant and must be handled as hazardous waste. To prevent the wrong lubricant or refrigerant from being installed during routine mobile HVAC system servicing, the service ports on air conditioning systems have been changed so that the service equipment for an R-12 system cannot be connected to an R-134a system (FIGURE 7-3).

H

FIGURE 7-2 HFC R-134a, tetrafluoroethane

molecule.

A

B

FIGURE 7-3 Different service ports: on A. R-12 and on B. R-134a.

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Refrigerants

Tetrafluoropropene (HFO R-1234yf) (R-1234fy)

79

F

Once it was discovered that R-134a was a major factor in the contribution of greenF house gases, the industry had to seek out yet another replacement refrigerant. The replacement refrigerant is R-1234yf, also referred to by the trade names Opteon H2C (DuPont) or Solstice (Honeywell). The chemical name of R-1234yf is tetrafluoroF F propene (CH2=CFCF3). R-1234yf is in the hydrofluoro-olefin (HFO) family of gases (FIGURE 7-4). This HFO was created to meet global regulations on decreasing environ- FIGURE 7-4 HFO R-1234yf, tetrafluoropropene mental damage and is the latest refrigerant for mobile HVAC systems. Although it has molecule. many of the same characteristics of R-134a, this new refrigerant has a much smaller global warming potential (GWP)—that is, a GWP of 4—than the GWP of 1,430 for R-134a refrigerant. Its atmospheric lifetime is only 11 days, whereas the atmospheric lifetime of R-134a is 13 years. It has a boiling point of −20.2°F (−29°C). It is slightly flammable, but the safety risk ▶▶FAST FACT has been determined to be significantly less than the risk associated with gasoline. Although HFO R-1234yf refrigerant uses a PAG-type oil, there are different additives than those found Opteon and Solstice were made as a joint in R-134a, so R-134a PAG oil will not work in R-1234yf systems. Polyolester (POE) oil is geneffort between two different companies, erally used for electrically driven compressors, but it has also been used in some belt-driven DuPont and Honeywell. In an effort to compressor applications. HFO T-1,234yf service ports are different than those used with R-12 help protect the environment and combine resources, they collaborated to creor R-134a, so contamination issues can be minimized (FIGURE 7-5). ate R-1234yf. HFO R-1234yf is costlier to produce than is R-134a, so that will impact customers as their systems need servicing. The average cost of R-1234yf is over $150 per pound, whereas R-134a averages $7 per pound.

Carbon Dioxide (R-744) Another alternative approved by the EPA as a replacement for R-134a is R-744, otherwise known by the chemical name carbon dioxide (CO2). Carbon dioxide is an odorless gas that is naturally occurring chemical substance with a GWP rating of 1. While this rating is excellent for the environment, the R-744 system requires elevated operating pressures of up

A

B

C

FIGURE 7-5 Different service ports: on A. R-12, on B. R-134a, and on C. R-1234yf.

Applied Science AS 7-1: Numbering Refrigerants—the technician has an understanding of the chemical composition of the refrigerant and how the refrigerants are numbered.

The R numbering system was developed by DuPont. Most refrigerants are classified as Class 1. Class 1 refrigerants are defined as refrigerants that provide cooling by changing its state of matter.

Refrigerants are given numbers based on their molecular mass, and there are a few rules. The numbering system is based on carbon, hydrogen, and fluorine molecules. It includes the number of carbon (C) molecules, regardless of how many of one molecule is subtracted. If the carbon is double-bonded, it is neither added nor subtracted but put in the first column. It includes the number of hydrogen (H) molecules, regardless of how many of one molecule is always added. Fluorine (F) is counted as is.

Examples: R-12 is CCL2F2. Using the numbering rules, 1 C (1 – 1 = 0), 0 H (0 + 1 = 1), and F = 2.

R= 012 or R-12.

R-134a is CF3CFH2. Using the rules, 2 C (2 – 1 = 1), 2 H (2 + 1 = 3), and F = 4. R = 134a. The “a” signifies an unbalanced atom, meaning there is an R-134 and an R-134a. Both have the same formula, just a different chemical arrangement.

R-1234yf is CH2 = CFCF3. Using the rules: 1 = 1 double bonded carbon, 3 C (3 – 1 = 2), 2 H (2 + 1 =3), and F = 4. R-1234yf.

R-744 is classified as a 700-series refrigerant, or inorganic with a molar mass of 44. This becomes R-744.

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Chapter 7 Air Conditioning Refrigerant and Refrigerant Oil

▶▶FAST FACT If air became saturated with as little as 10% CO2, this could cause suffocation.

This requires vehicle manufactures to design and implement special safety systems on vehicles equipped with a CO2 refrigeration system.

7-02 Describe the procedure to test for sealants in a mobile HVAC system.

FIGURE 7-6 A sealant detection kit.

to 10 times higher (from 600 psi to near 3,000 psi) than R-134a systems to operate properly.

This will require a completely new system design to enhance safety—along with service procedures and equipment, including leak detection. This refrigerant system will add a significant cost to the price of the vehicle and is currently being used only by German auto manufacturers on select models.

▶▶ Sealant

Detection

Before identifying the refrigerant in the system, a technician must test to determine whether sealant has been added to the vehicle’s air conditioning system. A sealant is an additive that is added to a refrigeration circuit to stop certain leaks. They work by either swelling up the fitting seals and O-rings or forming a “patch” over leaking areas when the sealant is exposed to air. Many small cans of refrigerant available to the “do it yourself ” consumer come with sealant inside, and if too much is installed, it can cause the system malfunctions or even create new leaks. Undetected sealer use can damage refrigerant identifiers and air conditioning machines.

Although a small number of vehicles have sealer in them, all it takes is one vehicle to contaminate and damage air conditioning equipment. Most experts agree that sealant should never be used. If there is a leak, the leak should always be repaired. Identifying whether the system has sealer in it should be the first step in the refrigerant-identifying process. A technician can use a sealant detector to test the refrigerant ­system (FIGURE 7-6).

To test for the presence of sealant by using a sealant detection test kit, follow the steps in SKILL DRILL 7-1.

SKILL DRILL 7-1 Testing for the Presence of Sealant by Using a Sealant Detection Test Kit 1. Select an appropriate refrigerant service port adapter.

2. Fill the syringe with tap water.

Continued

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Sealant Detection

81

3. Put water from syringe into both ends of the test cartridge.

4. Install the test cartridge on one end of the adapter and the test hose to the other end.

5. Install the flow meter on the other end of the hose.

6. Hang the flow meter from an easily viewed location.

Continued

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Chapter 7 Air Conditioning Refrigerant and Refrigerant Oil

7. Install the adapter to the high-side service port of the vehicle.

8. Watch for flow in the flow meter to stabilize.

9. Wait two to three minutes. If there is still flow indicated on the meter, there is no sealant detected. If flow has stopped or decreased, there is sealant in the system.

▶▶ Refrigerant

7-03 Describe the process for identifying refrigerants.

▶▶FAST FACT New R/R/R machines for R-1234yf will require the use of refrigerant identifiers.

If a mixture of less than 98% pure refrigerant is found, the machine will not allow the system to be recovered and a specialized recovery-only machine will be required.

Identification

The only way to determine the type of refrigerant in a system is with the aid of a refrigerant identifier. This easy-to-use device connects to the low-side air conditioning fitting and takes a reading of the refrigerant. It will give a readout such as 100% R-134a, or if the system is contaminated, it may give a reading such as 60% R-134a and 40% R-12. As long as the refrigerant is pure, it can be recycled by using a R/R/R machine and then reused. If it is contaminated by the wrong refrigerant or the wrong oil, then it is considered a hazardous waste and must be put in a separate unit and disposed of according to state law. The air conditioning sticker under the hood lists the type of refrigerant and how much should be in the system.

Refrigerant should be tested to determine its type any time the refrigerant will be recovered. If the refrigerant in the vehicle is contaminated and put in the recovery bottle of the

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Refrigerant Identification

air conditioning machine, the whole bottle in the machine is contaminated and should be treated as hazardous waste. If it is not caught while in the machine, it will contaminate every vehicle that has air conditioning refrigerant installed from that machine’s recovery bottle.

Due to the high number of contaminated and counterfeit refrigerants on the m ­ arket and installed in vehicles, it is recommended that all refrigerant purchased be from a ­reputable supplier. It is also recommended that all refrigerant purchased be tested for purity.

Be sure to tag or write the date tested and results of the test on the canister.

To identify the refrigerant type, follow the steps in SKILL DRILL 7-2.

▶▶TECHNICIAN TIP

83

It is recommended that an additional, external filter be added to all recovery equipment. This will help remove oil, dye, and contaminants. It is a small investment compared to the cost of the R/R/R machine.

SKILL DRILL 7-2 Identifying the Refrigerant Type 1. Use a sealant identifier to check whether there is any sealant in the system. If there is, notify your supervisor. Turn on the refrigerant identifier, and allow the machine to warm up.

2. Connect the refrigerant identifier to the low side of the air conditioning system, and open the service valve. Follow the Prompts on the refrigerant identifier, and record the refrigerant type and amount of air, if any.

3. Turn of the valve, and disconnect the refrigerant identifier. If the refrigerant does not match the under-the-hood sticker, recover the contaminated refrigerant into a contaminated tank that is properly labeled for disposal. If the refrigerant is 100% pure and matches the under-the-hood sticker, continue to the next step.

Continued

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Chapter 7 Air Conditioning Refrigerant and Refrigerant Oil

4. After selecting the pressure gauge set, make sure the service valves on the gauges are in the off or shut position.

5. Connect the service chuck of the pressure gauge to the air conditioning system. Open the valves, watch the high-and low-pressure gauges, and record the pressure. If the high-and low side gauges are the same pressure and you could not check for noncondensable gases, use the PT chart to determine that as follows.

6. Measure the ambient temperature (6–8" [15–20 cm] in front of the condenser) and the pressure on the pressure gauge set.

Compare the pressure to the PT chart for that type of refrigerant.

▶▶ Counterfeit 7-04 Explain counterfeit refrigerant and contaminated refrigerant disposal.

▶▶FAST FACT Propane and butane make excellent refrigerants but are not safe for mobile HVAC system use due to the high flammability and explosion risk. All flammable refrigerants have been banned by the Environmental Protection Agency (EPA).

and Contaminated Refrigerant

If a refrigerant is labeled or represented as one type, but is actually another, that refrigerant could be considered counterfeit. If refrigerant is mixed with another substance, even air, it should be considered contaminated. Counterfeit or contaminated refrigerant can be very costly, not only to the vehicle owner but to the repair equipment also. Imagine not testing a vehicle that a technician has serviced and the refrigerant that was recovered is contaminated. Every vehicle that is serviced from that point on with that equipment is now contaminated. The results of contamination may not be immediately discovered, but it will have an effect on system performance. The combination of refrigerants, moisture, and other chemicals will break down inside the refrigerant system, causing them to ­possibly change their chemical composition. This change will cause a decline in system performance or a failure that starts internally in the system that causes component

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Refrigerant Oils

damage. There is also the dangerous potential of changing the nonflammable refrigerant into a flammable substance.

When contaminated or counterfeit refrigerant is found, it must be handled with special care because it is classified as hazardous waste. The rules set by the EPA state that no refrigerant (except R-744) is allowed to be vented and must be recovered by specialized, dedicated machines and stored in a specific container.

Recovery Methods Currently, there are only two approved methods to recover contaminated or counterfeit refrigerants. The first is a recovery-only machine (FIGURE 7-7). These machines are built specifically for this purpose and include safety features such as non-sparking (to prevent the ignition of possibly flammable substances). The other approved method is to convert an existing R/R/R machine and dedicating it to only removing contaminated refrigerant.

The dedicated machine should also have the same spark-proof ratings to prevent accidental explosion or fire.

Storage Container Contaminated refrigerant should be stored in an approved container. The container should be approved by the DOT (the U.S. Department of Transportation), which can be identified by its appearance: gray with a yellow-painted top (FIGURE 7-8). The storage container should also be rated for flammable gases. When being filled, no container should be filled past 80% of total capacity at 77°F. This will allow room for expansion and increased internal pressure due to a rise in temperature. All containers should be properly labeled and stored above ground level since refrigerant is heavier than air. If containers are to be stored for long periods of time, they should be inspected monthly for damage and corrosion.

▶▶ Refrigerant

Oils

The oil used in refrigeration systems must be compatible with the refrigerant used. Oil is necessary to keep moving parts in the system and the compressor lubricated. Oil is also used on the gaskets, seals, and hoses to protect and help maintain system integrity. The oil must be able to move throughout the system without foaming and be compatible with the refrigerant and the pressure changes taking place. The oil is picked up and carried throughout the system in the refrigerant, so some oil will be found in all the major air conditioning system components (compressor, evaporator, receiver-drier or accumulator, and condenser). The oil in the compressor is just as important as oil in an engine. Without it, the compressor will overheat and destroy itself. There are now four different types of refrigerant oils: m ­ ineral oil, PAG, POE, and PVE (polyvinyl ester). Each oil can have a different ­viscosity (how thick or thin the oil is and how it flows at different temperatures). Always refer to service information and the underhood sticker for correct oil specifications.

85

▶▶FAST FACT Contaminated refrigerant affects not only automotive repair but all refrigeration systems across the world. For example, the U.S. Army recently found that locally sourced refrigerant used in refrigerant system repairs oversees was counterfeit.

Nearly 20 different counterfeit refrigerants were discovered, including R-40, which is extremely harmful. When R-40 comes in contact with aluminum, it forms a highly explosive substance called trimethylaluminum (TMA). TMA will spontaneously ignite when exposed to air. By the time the contamination was discovered, up to 25% of U.S. Army vehicles had refrigerant contamination. The U.S. Army has now implemented a field testing kit to test all refrigerant being used for repairs, but the damage was done. The repairs needed could prove to be very costly, with approximately 2,000 pounds (910 kg) of new refrigerant and up to a complete refrigerant system replacement on every vehicle.

▶▶FAST FACT Recovery and recycling machines do not have the ability to separate contaminated refrigerants. Per EPA guidelines, ­contaminated refrigerants must be sent to an approved waste hauler or approved refrigerant reclaimer for either reclamation or destruction. Refer to the EPA for an approved list. The cost for this service could become expensive, stressing the need to test every vehicle serviced and container purchased.

7-05 Identify the different types of refrigerant oils used in mobile HVAC systems.

FIGURE 7-7 A non-sparking recovery-only

FIGURE 7-8 A DOT-approved contaminated refrigerant

machine.

storage container.

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Chapter 7 Air Conditioning Refrigerant and Refrigerant Oil

▶▶TECHNICIAN TIP A disposable container must never be refilled at any time. Disposable containers are for shipping of reclaimed or virgin refrigerant only. When in doubt, look for the words “DOT” and “refillable” on the container. If they are not on the container, do not use that container.

▶▶TECHNICIAN TIP All refrigerant oils are considered ­hygroscopic (they absorb moisture), some more than others. When done using a container of refrigerant oil, the cap should be secured tightly to prevent contamination. Moisture contamination can lead to internal system corrosion and system failure.

FIGURE 7-9 Container of mineral oil.

Mineral Oil Mineral oil is a highly refined oil that is used in R-12 refrigerant systems. It has a clear to light yellow appearance and almost no odor (FIGURE 7-9). There are two different viscosities used for R-12 systems: 500 and 525.

PAG (Polyalkylene Glycol) Oil ▶▶FAST FACT Mineral oil is not compatible with any other refrigerants, because it is not ­miscible (able to mix). If mineral oil were to enter a system, the oil would separate from the refrigerant and build up elsewhere in the system. This would prevent the proper amount of oil from being in the compressor and cause compressor damage. However, some manufacturers who use other refrigerants recommend lubricating O-rings and seals during system repair with mineral oil. This is due to the higher alcohol content of the other refrigerant oils, which might damage those seals. Small amounts of mineral oil from an O-ring that might enter the ­system will not cause any damage.

PAG oil is a synthetic (human-made) oil used in R-134a refrigerant systems. It has a light blue color and almost no odor. As the oil picks up dirt or becomes c­ ontaminated, it will turn brown or black, depending on the level of contamination. PAG oil for R-134a systems can be found today in three different viscosities: PAG 46, PAG 100, and PAG 150 (FIGURE 7-10). PAG 46 has the lowest viscosity rating and is the most c­ ommon PAG oil used. PAG 100 has a medium viscosity and is the second most used PAG oil. PAG 150 is the highest viscosity oil used, mainly in older GM vehicles. R-1234yf refrigerant systems now call for a new PAG oil. This new PAG oil (FIGURE 7-11) has an additive package (of acid reducers) installed. Each vehicle manufacturer has developed its own specifications for the oil, depending on the model of compressor used on the system.

Care should be taken with PAG oil because it can cause skin irritation and paint damage. PAG oil is also very hygroscopic: It can absorb a large amount of

▶▶FAST FACT R-1234yf PAG oils will not be as universal as current R-134a PAG oils. For example, Chrysler currently has three different R-1234yf PAG oils for its current vehicles, whereas GM has two. That number is expected to change as vehicle manufacturers introduce new vehicles into the market with R-1234yf refrigerant.

FIGURE 7-11 Container FIGURE 7-10 Containers of R-134a PAG oil.

of R-1234yf PAG oil.

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Refrigerant Oils

87

moisture quickly. When moisture enters the refrigerant system, it begins the process of hydrolysis (a chemical breakdown due to reaction with water). The oil can then change into other compounds, such as hydrochloric acid, and start to damage the system internally. ▶▶TECHNICIAN TIP Using the wrong PAG oil could create a short circuit, causing high voltage to pass through the compressor.

That voltage could cause an electrocution injury or death to the vehicle operator or service technician. It was widely believed that PAG oil should never be used in a hybrid vehicle. However, some German auto manufacturers are now using a specifically formulated PAG oil for use in their hybrid vehicles. Always be sure to check the most current service information for the correct application.

Polyolester Oil Polyolester (POE) oil is also a synthetic oil used in R-134a refrigerant and some R-1234yf systems. It has a clear appearance and slight odor and is available in only one viscosity (FIGURE 7-12). POE oil is also very hygroscopic, but not to the level of PAG oil. POE oil was chosen for system retrofit from R-12 to R-134a because it does not change chemical properties when exposed to R-12. POE oil is primarily used for high voltage compressors due to its electrical insulating properties (FIGURE 7-13). However, it is now showing up on some belt-driven compressors. ▶▶TECHNICIAN TIP Hybrid HVAC systems require special service and attention. For example, the Chevrolet Volt requires an HVAC system flush and refill service and desiccant replacement at 10 years of being in operation.

Some hybrids even monitor the refrigerant system, and if a slight amount of PAG oil is found, the “Check Engine” light may illuminate and the vehicle may be prevented from running. Some R/R/R machines now have a special flush feature to prevent PAG oil from entering POE systems during refrigerant system service.

Polyvinyl Ether Oil PVE oil (FIGURE 7-14) is also a new synthetic oil that has been adapted for use in some Korean-built hybrid vehicles. It is compatible with R-134a and R-1234yf refrigerant systems.

PVE oil was formulated to achieve excellent electrical insulating properties and is both less hygroscopic and hydrolysis resistant. It has a viscosity rating of 68 and is ­comparable in cost to both PAG and POE oils.

FIGURE 7-12 Container of

R-1234yf PAG oil.

FIGURE 7-13 Container of hybrid POE oil.

FIGURE 7-14 Container

of hybrid PVE oil.

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Chapter 7 Air Conditioning Refrigerant and Refrigerant Oil

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Refrigerant is the component responsible for absorbing heat from and releasing heat to the vehicle.

R-12, also known by the trade name “Freon,” was a commonly used refrigerant until early 1994.

R-12 is a CFC, a compound that was found to be damaging the ozone layer.

R-134a, also known by the trade name “Suva,” was the chosen replacement for R-12 for both new vehicle and retrofit applications.

R-134a is a contributor to the earth’s greenhouse gases and will no longer be used as a refrigerant in new vehicle production past the 2021 model year.

R-1234yf, also known by the trade names “Opteon” and “Solstice,” is the newest and most environmental friendly refrigerant used in vehicles to date.

Each type of refrigerant has its own unique service ports and caps, along with a unique type of oil.

R-744 refrigerant, or carbon dioxide, is being considered as an alternative refrigerant, but they require an entirely new system due to the high operating pressures.

Refrigerant system sealant can be added to a system to stop leaks, but it can cause severe damage and contamination to shop equipment. Sealant detectors help identify the presence of sealant to protect expensive equipment.

Refrigerant identifiers must be used to determine if a refrigerant system is safe to be handled by equipment.

Contaminated or counterfeit refrigerant can cause damage and incur expensive repairs.

Any contaminated refrigerant must be handled as hazardous waste.

R-1234yf R/R/R machines are required to have an onboard refrigerant identifier that must be used before a system can be recovered.

Contaminated refrigerant must be recovered by ­specialized or dedicated equipment and stored in a gray ­container with a yellow-painted top.

Each refrigerant has its own unique type of oil and must never be mixed together.

Refrigerant oils are hygroscopic and should be used only from a sealed container.

PAG oils are rated by their viscosity.

Hybrid vehicles require a special oil that resists electrical current flow. If a system recognizes that the wrong oil has been installed or the system is contaminated, the vehicle may not start.

PVE oil is a new oil used by Korean manufacturers in their hybrid vehicles.

Key Terms carbon dioxide (CO2) One of the resulting gases produced when burning a hydrocarbon fuel, which contributes to global warming.

chlorofluorocarbon A chlorine-based fluorocarbon compound. dichlorofluoromethane A CFC refrigerant, also known as R-12 or Freon.

Freon See dichlorofluoromethane hydrofluorocarbon A chlorine-based fluorocarbon compound with hydrogen. hydrofluoro-olefin A chemical compound that uses hydrogen, flourine and carbon with a double chemical bond that makes it more stable, giving it a low GWP hydrolysis The use of electricity to break down water into its oxygen and hydrogen gas components. hygroscopic A property of a substance or liquid that causes it to attract and absorb moisture (water), as a sponge absorbs water.

Brake fluid absorbs water out of the air; thus it is hygroscopic. miscible The ability of a substance to mix. opteon The brand name of R-1234yf by Chemours (formerly Dupont). polyolester (POE) oil An oil typically used in hybrid, or electric compressors. refrigerant The name given to a chemical compound designed to meet the needs of the refrigeration system.

R-12 An inert, colorless gas that can be used as a refrigerant. It is stored in white containers. sealant A substance that, when it comes in contact with moisture, will slow a leak down. solstice The brand name of R-1234yf by Honeywell. synthetic A substance that is human-made and not found naturally on the earth. tetrafluoroethane An inert, colorless gas that can be used as a refrigerant. It is stored in light blue containers. tetrafluoropropene An HFO refrigerant, also known as R-1234yf. trimethylaluminum (TMA) A highly explosive substance that is created when R-40 refrigerant comes into contact with aluminum. viscosity The measurement of how easily a liquid flows; the most common organization that rates lubricating fluids is SAE.

Review Questions 1. Which of the following is not a refrigerant being used in mobile HVAC systems? a. Propane. b. Tetrafluoroethane. c. Dichlorofluoromethane. d. Tetrafluoropropene.

2. R-12 was banned from being used in new vehicle production starting in what year? a. 1970. b. 1994. c. 1996. d. 2021.

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Wrap-Up

3. All of the following are true about R-744 as a refrigerant except a. It has a global warming potential (GWP) rating of 1. b. CO2 is a naturally occurring chemical substance. c. It has a very strong odor. d. It operates at very high pressures.

4. Which of the following is not true about refrigerant sealant? a. Most experts agree it should not be used. b. A sealant detector uses water to test for the presence of sealer. c. It can be installed by a consumer. d. All of the above are true.

5. Which of the following is not true about contaminated refrigerant? a. It should be handled as hazardous waste. b. It must be recovered with specialized, dedicated equipment. c. Contaminated refrigerant can be filtered and then reused. d. It must be stored in a gray container with a y­ ellow-painted top.

6. Which of the following oils should be used with R-12 refrigerant? a. PVE oil. b. Mineral oil. c. PAG oil. d. PVC oil.

7. ______________ should be installed on an R/R/R machine to aid in the removal of oil, dye, and contaminates. a. An external filter b. A refrigerant identifier c. A sealant detector d. An oil separator 8. Which of the following is not a PAG oil viscosity? a. 46. b. 68. c. 100. d. 150.

9. What oil is used with both R-134a and R-1234yf? a. PAG. b. POE. c. Both A and B. d. Neither A nor B. 10. __________ is the stable chemical that is used for heat transfer by changing back and forth from a gas into a liquid. a. Mineral oil b. Polyalkylene glycol c. Polyol ester d. Refrigerant

ASE Technician A/Technician B Style Questions 1. Technician A says that mixing PAG oil with mineral oil will create hazardous waste. Technician B says that unique service ports make it impossible to install the wrong refrigerant in a vehicle. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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2. Technician A says that R-12 is a hydrofluorocarbon. ­Technician B says that R-12 is still available to purchase today. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 3. Technician A says that R-134a was chosen as a replacement for R-12. Technician B says that R-1234yf was chosen as a replacement for R-134a. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 4. Technician A says that a vehicle’s refrigerant should always be tested for purity before installing expensive refrigerant-­ handling equipment? Technician B says that a test for the presence of sealant should also be performed before installing expensive refrigerant-handling equipment. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 5. Technician A says that R-134a has a GWP of 13 days. ­Technician B says that R-1234yf has an atmospheric lifetime of 13 years? Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 6. Technician A says PAG oil can be used in both R-134a and R-1234yf systems. Technician B says that although PAGtype oil can be used in both refrigerant systems, R-1234yf has different additives and should not be used in R-134a systems. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 7. Technician A says R-1234yf R/R/R machines will not allow a system to be recovered if less than 98% pure refrigerant is found. Technician B says that any machine is capable of removing refrigerant from any system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B 8. Technician A says propane and butane are excellent refrigerants and can be used in all applications. Technician B says that propane and butane are highly flammable and have been banned by the EPA due to the high flammability and explosion risk. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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Chapter 7  Air Conditioning Refrigerant and Refrigerant Oil

9. Technician A says that R-40 refrigerant is safe to use in any system. Technician B says that contaminated refrigerant must be removed with a non-sparking feature, to prevent igniting a flammable substance. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

10. Technician A says R/R/R machines do not have the ability to separate contaminated refrigerants. Technician B says that all storage containers for contaminated refrigerants should be rated for flammable gases. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B

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MASTER AUTOMOTIVE TECHNICIAN SERIES

SAMPLE CHAPTERS 6 and 7

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