EPA Section 608 FAQ
EPA-Approved Section 608 Certification is needed to service building air conditioning and refrigeration systems.
EPA Section 608 FAQ
- FAQ Home
- General Questions
- Certification Questions
- Software Practice Exam Corrections
- Updates to the Manual & EPA Law Changes
- Technical Questions
- Is Mainstream Engineering approved by the EPA to offer Clean Air Act Section 608 certification?
- What type of A/C systems am I certified to work on with each type of certification?
- Is EPA Certification valid in countries other than the United States?
- What type of Certification do I need to purchase refrigerants?
- What is a Type I Certification?
- What is a Type II Certification?
- What is a Type III Certification?
- What is a Universal Certification?
- What is the difference between Type I and Type I Open Book?
- Do I need to retake the core portion of the 608 exam if I’m Type I Open Book certified and I’m going for my Type II, Type III, or Universal Certification?
Software Practice Exam Corrections
- The recovery of refrigerant from a system as a vapor-only will minimize the loss of: ????
- The EPA Section 608 certification must be renewed every: ????
- For a single-phase compressor, the ???? capacitor is only in the circuit for a short period of time and then is cut out of the circuit.
- According to the EPA, there is approximately ???? refrigerant vapor left in an average 350 ton R- 11 chiller at 0 psig pressure once all the R-11 liquid has been removed?
- When a system is operating, refrigerant enters the expansion device as a ????
- Which refrigerant does not need to be recovered?
- ???? is a potential refrigerant for a low-pressure chiller.
- ??? will speed up recovery.
Updates to the Manual & EPA Law Changes
- EDITION 1 of the “Expanded Full Color Edition” – Correction to practice questions #23 – #26 on page 193.
- EDITIONS 1-16 – Correction to practice question #79 on the second practice test in the back of the book.
- EDITIONS 4-13 – Correction on or near p. 94
- EDITIONS 1-12 – Appliance Evacuation Level Change
- EDITIONS 1-12 – Changes to the Evacuation Requirements, Reclassification of R-410A for Evacuation Purposes, and confusion over the EPA Test Questions
- EDITIONS 1-13 and Edition 1 of the “Expanded Full Color Edition” – Clean Air Act Violation Fine Change
- EDITIONS 1-12 – Practice Exam #2, Question #47 Correction
- The EPA Certification manual claims that there are no drop-in substitutes for refrigerant but I’ve seen refrigerant products that claim otherwise. Can you explain what’s going on?
- Using the saturation pressure-temperature chart, the pressure is higher that the saturation pressure given on the chart for the measured temperature and I am sure the pressure and temperature readings are correct. What is going on here?
- Please explain how a basic (vapor-compression) refrigerator, air conditioner or heat pump works.
- Please Explain the Refrigerant Numbering System.
- Why are some refrigeration containers green and others are blue or white?
- Is the use of R-12 (also called CFC-12) banned?
- Can I vent HFC-134a or other refrigerant substitutes?
- Is R-134a flammable?
- Are there any Drop-In Replacement Refrigerants for R-12?
- What refrigerants are used now? What is Freon?
- Before you charge a system, do you need to use a pressure decay leak test?
1. Is Mainstream Engineering approved by the EPA to offer Clean Air Act Section 608 certification?
Yes, you can find Mainstream Engineering as an approved organization on the EPA’s website for Section 608 Technician Certification Programs.
3. What type of A/C systems am I certified to work on with each type of certification?
608 HVAC Type I certification certifies you to work on unitary small appliances containing five pounds or less of refrigerant. 608 HVAC Type II certification certifies you to work on high-pressure and very high-pressure appliance which includes split systems and all other non-automotive systems not covered under the category of unitary small appliance or low-pressure appliance. 608 HVAC Type III certification certifies you to work on low-pressure appliances, such as chillers. 609 MVAC certification is required to work on Motor Vehicle A/C units.
4. Is EPA Certification valid in countries other than the United States?
No, it is not. The EPA is an U.S. agency and therefore is only valid in the U.S.
5. What type of Certification do I need to purchase refrigerants?
If you get a 608 certification (Type I, Type II, Type II, or Universal), you can buy any refrigerant sold in an HVAC/R store in containers of 20 pounds or more. If you get 609 certification you can buy any refrigerant sold in an automotive supply house in any size container, however these stores typically only sell R-12, R-134a and replacement blends for R-12.
1. What is a Type I Certification?
Technicians receiving a passing grade on the Type I (small appliance) examination are certified to recover refrigerant during the maintenance, service or repair of packaged terminal air conditioners with 5 pounds or less or refrigerant. Only Type I or Universal certified technicians can recover refrigerant from these units. The Type I certification is available in an open-book exam, as well as the closed book format. To become Type I Certified you must pass the Core and Type I sections of the 608 exam.
2. What is a Type II Certification?
Technicians receiving a passing grade on the Type II (medium-, high-, and very high-pressure) examination are certified to recover refrigerant during the maintenance, service or repair of high-pressure equipment (Medium-Pressure R-12, R-114, R-134a, R-401A and R-500; High-Pressure R-22, R-502, R-402A, R-402B, R-404A, R-407A, R-407B, R-407C, and R-410A; and Very-High-Pressure R-13, R-23, and R-503). Only Type II or Universal certified technicians can recover refrigerant from these units. To become Type II Certified you must pass the Core and Type II sections of the 608 exam.
3. What is a Type III Certification?
Technicians receiving a passing grade on the Type III (low-pressure appliance) examination are certified to recover refrigerant during the maintenance, service or repair of low-pressure equipment (CFC-11, HCFC-123). Only Type III or Universal certified technicians can recover refrigerant from these units. To become Type III Certified you must pass the Core and Type III sections of the 608 exam.
4. What is a Universal Certification?
Technicians receiving a Universal Certification are certified to recover refrigerant during the maintenance, service or repair of small appliances, high-pressure equipment and low-pressure equipment. That is, they are certified to work on any type of air conditioning and refrigeration equipment except motor vehicle air conditioning. To become Universal Certified you must pass the Core, Type I, Type II, and Type III sections of the 608 exam.
5. What is the difference between Type I and Type I Open Book?
In terms of the certification itself, nothing. A Type I Open Book Certification is a Type I Certification and they both enable you to do the same thing. The difference is in the core section only, an unproctored (open book) grade for the core section will not count towards a Type II, Type III, or Universal certification. Therefore, if a Type II, Type III or Universal Certification is desired you must retake and pass the core section in the proctored environment. See the table below to determine which exams you need to take to reach your desired certification level:
6. Do I need to retake the core portion of the 608 exam if I’m Type I Open Book certified and I’m going for my Type II, Type III, or Universal Certification?
YES! The Open Book core portion of the exam is good ONLY for the Type I Open Book Certification. See the above table to see what sections you need to pass in order to reach a desired certification level.
Software Practice Exam Corrections
1. The recovery of refrigerant from a system as a vapor-only will minimize the loss of: ????
The correct answer is oil, not water as noted in the software practice questions.
2. The EPA Section 608 certification must be renewed every: ????
Currently the EPA certification has no expiration date, the correct answer is “D”.
3. For a single-phase compressor, the ???? capacitor is only in the circuit for a short period of time and then is cut out of the circuit.
The correct answer is in fact “B” the *Start* Capacitor. The Start Capacitor is only in the circuit for a short period of time, and is cut out of the circuit by the Start Relay (also referred to as the Potential Relay). The Run capacitor is always in the circuit and the Start Capacitor is switched in only during starting, as stated in the manual.
4. According to the EPA, there is approximately ???? refrigerant vapor left in an average 350 ton R-11 chiller at 0 psig pressure once all the R-11 liquid has been removed?
The correct answer is 100 lbs. The point the EPA is trying to make here is that even after all the liquid refrigerant has been removed from a very large chiller, there is still quite a lot of refrigerant left in the chiller. For example at 85°F, the density of the R-11 vapor is 0.357 pounds per cubic foot. Therefore, if the total volume of the refrigerant circuit in the chiller (including the condenser and evaporator barrels) was 280 cubic feet, then the mass of refrigerant contained would be 100 pounds (280 ft3 x 0.357 Lb/ft3 = 100 lb). While the inside volume of the average 350 ton chiller may not be quite as large as 280 cubic feet, it is the exam choice closest to an actual case.
5. When a system is operating, refrigerant enters the expansion device as a ????
The correct answer is “A” it enters the expansion device as a “subcooled or saturated liquid.” Refrigerant is condensed in the condenser, and it is usually subcooled slightly when it exits the condenser. It then flows thru the tubing to the inlet of the expansion device, such as the TXV or Cap tube as either saturated liquid or subcooled liquid.
6. Which refrigerant does not need to be recovered?
The correct answer is “D” both A and B are correct. Carbon Dioxide does not need to be recovered and R-744 is Carbon Dioxide, so the correct question is Both, since they are both Carbon Dioxide.
7. ???? is a potential refrigerant for a low-pressure chiller.
The correct answer is “B, R-123.” R-1234yf is a replacement for centrifugal chillers that use R-134a, these are NOT low pressure chillers. R-123 is a replacement refrigerant for LOW pressure chillers.
8. ???? will speed up recovery.
Lowering the temperature of the recovery tank, lowers the tank pressure so recovery is faster. Heating the system (where the refrigerant is being removed) also raises the system pressure and speeds recovery. Its simple, lower the pressure difference between system and recovery tank means faster recovery, you lower the pressure difference by either (or both) raising the system pressure and lowering the recovery tank pressure.
Updates to the Manual & EPA Law Changes
1. EDITION 1 of the “Expanded Full Color Edition” – Correction to practice questions #23 – #26 on page 193:
These four questions all refer to “Group 1”, “Group 2”, “Group 3”, and “Group 4” refrigerants. This is an erroneous reference. The questions should be providing ASHRAE safety classifications as possible answers instead. ASHRAE safety classifications are broken down by the letters “A” or “B” which designate relative toxicity and numbers “1”, “2”, and “3” designating relative flammability.
“A” refrigerants are relatively lower toxicity while “B” refrigerants are relatively higher toxicity.
“1” refrigerants have no flame propagation, “2” refrigerants have low flammability, and “3” refrigerants have high flammability.
The safety classification letters and numbers are grouped together. Therefore an “A1” refrigerant is non-flammable and of lower toxicity while a “B3” refrigerant is highly flammable and has a higher toxicity.
Review pages 95-99 in the manual for explanations to the questions on page 193.
2. EDITIONS 1-16 – Correction to practice question #79 on the second practice test in the back of the book:
CFCs can no longer be manufactured or imported into the United States after ____. The book provides four options, 1993, 1996, 2001, 2010. The correct answer is 1995. CFCs can no longer be manufactured or imported into the United States effective January 1, 1996. Since the question is asking AFTER a certain year, the answer would be CFCs can no longer be manufactured or imported into the United States after 1995.
3. EDITIONS 4-13 – Correction on or near p. 94:
The reference manual has a bullet point on or around p. 94 that states “According to the EPA, there is approximately 5 pounds of refrigerant vapor left in an average 350 ton chiller at 0 psig (14.7 psia) once all of the liquid refrigerant has been removed.” 5 pounds of refrigerant is not correct, the correct answer is 100 pounds. The point the EPA is trying to make here is that even after all the liquid refrigerant has been removed from a very large chiller, there is still quite a lot of refrigerant left in the chiller. For example at 85°F, the density of the R-11 vapor is 0.357 pounds per cubic foot. Therefore, if the total volume of the refrigerant circuit in the chiller (including the condenser and evaporator barrels) was 280 cubic feet, then the mass of refrigerant contained would be 100 pounds (280 ft3 x 0.357 Lb/ft3 = 100 lb). While the inside volume of the average 350 ton chiller may not be quite as large as 280 cubic feet, it is the exam choice closest to an actual case.
4. EDITIONS 1-12 – Appliance Evacuation Level Change:
The reference manual states “Appliances do not need to be evacuated all the way to the prescribed level if the appliance is being disposed of”. This statement is no longer correct.
5. EDITIONS 1-12 – Changes to the Evacuation Requirements and confusion over the EPA Test Questions
Originally, there were three categories of refrigerant based on the saturation pressure of the refrigerant, namely Low Pressure, High Pressure and Very High Pressure refrigerants. Several years ago the EPA proposed changing the definitions to subdivide the high pressure refrigerants into two categories namely Higher-Pressure and High Pressure. When this was done refrigerants, such as R-22, R-402, R-404, R-407 and R-502 became Higher-Pressure refrigerants with lower evacuation requirements, compared to the remaining High Pressure refrigerants.
On March 12, 2004, the EPA further changed the definitions by renaming High Pressure Refrigerant to Medium Pressure refrigerants and renaming Higher-Pressure refrigerants to High-Pressure refrigerants. This change leaves four categories of refrigerant defined below.
Low-Pressure Appliance – (definition unchanged by the EPA’s March 12, 2004 rule change) An appliance that uses a refrigerant with a liquid phase saturation pressure below 45 psia at 104°F. Evacuation requirements for the low-pressure category apply to these appliances. This definition includes but is not limited to appliances using R-11, R-113, and R-123.
Medium-Pressure Appliance – (prior to March 12, 2004, referred to by the EPA as high-pressure appliance) An appliance that uses a refrigerant with a liquid phase saturation pressure between 45 psia and 170 psia at 104°F. R-114 appliances are at the low-pressure end since the saturation pressure of R-114 at 104°F is slightly above 45 psia. This definition includes but is not limited to appliances using R-12. R-114, R-124, R-134a, R-401C, R-406A and R-500.
High-Pressure Appliance – (prior to March 12, 2004, referred to by the EPA as higher-pressure appliance) An appliance that uses a refrigerant with a liquid phase saturation pressure between 170 psia and 355 psia at 104°F. This definition includes but is not limited to appliances using R-22, R-401B, R-402A/B, R-404A, R-407A/B/C, R-408, R- 409, R-410A, R-411A/B, R-502 and R-507A.
Very High-Pressure Appliance – (definition unchanged by the EPA’s March 12, 2004 rule change) An appliance that uses refrigerants with a critical temperature below 104°F or with a liquid phase saturation pressure above 355 psia at 104°F. This category includes but is not limited to appliances using R-13, R-23, R-503.
The EPA has not formally ruled as to whether an appliance using R-410A is considered a “Very High-Pressure Appliance” or a “High-Pressure Appliance”, however Mainstream has investigated the issue and has concluded that R-410A should be considered a “High-Pressure Appliance” and the evacuation of R-410A appliances should adhere to the requirements for all “High-Pressure Appliances”
The EPA examination questions (created by the EPA not Mainstream), were not updated to reflect this change. For example, an EPA question might ask what vacuum you must evacuate a system with 100 pounds of R-502 using a recovery device manufactured after November 15, 1993. According to the current law the required vacuum is 0 Inches of Vacuum, but this choice is not on the older exams (which may still be in circulation), since when the exam was written there was only one class of high pressure refrigerants and the required evacuation level was 10 inches of vacuum. Alternatively, if the EPA exam asks what vacuum you must evacuate a system with 100 pounds of R-500 using a recovery device manufactured after November 15, 1993 the requirement has not changed since R-500 is still classified as a high-pressure refrigerant, and the correct answer remains 10 inches of vacuum.
6. EDITIONS 1-13 and EDITION 1 of the “Expanded Full Color Edition” – Clean Air Act Violation Fine Change
Violation of the Clean Air Act, including the knowing release of refrigerant during the maintenance, service, repair, or disposal of appliances, can result in fines up to $37,500 per day per violation. This fine was originally $25,000, increased to $27,500, then increased to $32,500 and, with the most recent rule change, increased to the current amount of $37,500. Some older paper exams might still use the $25,000, $27,500, or $32,500 fines, you should choose the original amount as the EPA has not updated the questions to reflect the changing laws.
7. EDITIONS 1-12 – Practice Exam #2, Question #47 Correction
Question # 47 reads:
“When using recovery and recycling equipment manufactured AFTER November 15, 1993, technicians must evacuate an appliance component containing very high-pressure refrigerants, such as CFC-113 and -503, to _____ of mercury vacuum before making a major repair, independent of the quantity of refrigerant in the system.” CFC-113 should be CFC-13.
1. The EPA Certification manual claims that there are no drop-in substitutes for refrigerant but I’ve seen refrigerant products that claim otherwise. Can you explain what’s going on?
The EPA position is that there are no direct drop-in replacements. This statement means that nothing has to be changed on the system, and the performance is identical. While refrigerant blends have been engineered to have very similar pressure-temperature profiles, they are not drop-in replacements since the system operates differently (different capacity, COP, etc.) when used, and the controls, filter-drier, superheat adjustment, fan speeds, etc., may have to be changed to optimize performance on the replacement refrigerant.
2. Using the saturation pressure-temperature chart, the pressure is higher than the saturation pressure given on the chart for the measured temperature and I am sure the pressure and temperature readings are correct. What is going on here?
If the pressure is more than 10% above the saturation pressure you COULD have a non-condensable problem. (read the saturation pressure/temperature off the gauges if a table is not handy, a table is presented below). An easy way to calculate this 10% is to simply divide the pressure by 10 then add it to the pressure. For example for an R-22 system, if the temperature on the surface of the condenser is 95F (saturation pressure is 179 psig) and the pressure above (180+18 = 198) 198 psig then you COULD have some non-condensables in your system (or you have an inaccurate pressure or temperature gauge). If you suspect non-condensables on a low pressure unit, check the purge unit. If it is not a low pressure unit, it is RARE than you would have a non-condensable problem since there are only two ways to get non-condensables into a high-pressure system: It was introduced during servicing (Since the system’s pressure is always above the ambient pressure that means air and other junk can’t leak in.) or the refrigerant and/or oil broke down to form non-condensables (acids) and sludge- but this will show up in the QwikCheck Acid Test. However if sufficient acid was formed so as to cause a noticeable non-condensable pressure build-up, you will have a compressor burn out in your VERY near future.
a Indicates a vacuum in inches of mercury.
b Critical point @ 67F.
3. Please explain how a basic (vapor-compression) refrigerator, air conditioner or heat pump works.
The most basic vapor-compression refrigeration system consists of four major components: compressor, evaporator, condenser, and expansion device. As every technician knows, actual practical hardware contains many other critical components for reliable, trouble-free operation, such as a control system, high-pressure and low-pressure safety controls, liquid receiver, accumulator, oil separator, crankcase pressure regulator, etc. However, the four basic components are all that is needed to illustrate how a system operates. In the basic cycle, slightly subcooled liquid refrigerant leaves the condenser at high pressure, and the pressure is dropped via the throttling device (capillary tube, TXV, etc.) before it enters the evaporator. It enters the evaporator as two-phase mixture (mostly liquid with some vapor) and evaporates or boils at low temperature, adsorbing heat.
Refrigerant adsorbs energy (provides cooling) as it is evaporated, that is, as it boils and turns from liquid to vapor it absorbs energy thereby providing the cooling. For pure refrigerants, if the refrigerant evaporates at a constant pressure, then the evaporation occurs at a constant temperature while both liquid and vapor are present. Likewise refrigerant rejects energy (gives off heat) as it condenses from vapor to liquid. For pure refrigerants and azeotropic mixtures (500 series refrigerants), if the condensation occurs at a constant pressure, then the condensation will occur at a constant temperature until all the vapor has condensed to a liquid. Therefore, for evaporation, or condensation, the temperature and pressure are related by the pressure/temperature saturation curve.
Slightly superheated refrigerant vapor exits the evaporator and enters the compressor where the pressure and temperature are increased as the compressor compresses the refrigerant vapor. The vapor leaving the compressor is superheated vapor, and the compressor discharge is the hottest point in the cycle. This superheated refrigerant is cooled and condensed to a liquid in the condenser where heat is rejected (removed from the refrigerant and dumped into the air on an air cooled condenser). The refrigerant is condensed to liquid and subcooled slightly in the condenser. Refrigerant actually leaves the condenser slightly subcooled to assure condensation has been complete. Any non-condensable vapors in the system will be unable to condense in the condenser and will appear as gas bubbles in the condensed liquid stream. These non-condensables may collect in the condenser and displace refrigerant from the condenser, thereby reducing the effective surface area of the condenser.
Any water in the system will most likely freeze in the expansion valve because this is the point where refrigerant is cooled by the evaporation occurring as a result of the sudden pressure drop, and the expansion device also represents the smallest passageway in the overall system. It is this reason why filter/dryers are typically located just upstream of the expansion device.
4. Please Explain the Refrigerant Numbering System
Because the chemical names of typical refrigerants are long and complex, a method of referring to refrigerants by number was developed by DuPont. The numbering system was released for general use in 1956 and has become an industry standard. A complete discussion of the number designation and safety classification of the refrigerants is presented in ASHRAE Standard 34-1989.
Briefly, the method of designating a refrigerant by number is as follows. (Note that the numbering system begins on the right.)
First digit on the right = Number of fluorine atoms
Second digit from the right = Number of hydrogen atoms plus one
Third digit from the right = Number of carbon atoms minus one (not used when equal to zero)
Fourth digit from the right = Number of unsaturated carbon-carbon bonds in the compound (not used when equal to zero)
When bromine is present in place of all or part of the chlorine, the same rules apply except that the capital letter “B” after the designation for the parent compound shows the presence of the bromine (Br). The number following the letter “B” shows the number of Bromine atoms present. The lower-case letter that follows the refrigeration designation refers to the form of the molecule when different forms (isomers) are possible, with the most symmetrical form indicated by the number alone. As the form becomes more and more unsymmetrical, the letters a, b, and c (lower case) are appended (For example, HFC-134a). If all of the carbon bonds are not occupied by fluorine or hydrogen atoms, the remainder are attached to chlorine. Because the structure of a refrigerant, whether CFC, HCFC, or HFC, has become so important, they are often referred to in this way. For example, R-12 is CFC-12; R-22 is HCFC-22; R-134a is HFC-134a. This is simply a way of pointing out their chemical structure and therefore their relative ozone-depletion potential.
5. Why are some refrigeration containers green and others are blue or white?
Refrigerant manufacturers and packagers voluntarily color code cylinders for their chlorofluorocarbon refrigerant products. The color coding for common chlorofluorocarbon refrigerants is listed below. Those green containers contained HCFC-22 (R-22), the light blue containers contained HFC-134a, and the white containers contained CFC-12 (R-12).
6. Is the use of R-12 (also called CFC-12) banned?
No. The production or importation of CFC-12 in the USA is banned because according to the EPA it depletes the Ozone layer. However, use of CFC-12 is not banned. Even though production of CFC-12 ended on December 31, 1995, use of CFC-12 is still permitted and both recycled R-12 and R-12 manufactured before the Production Ban is still readily available. You can continue to use the CFC-12 that is in your vehicle now, and your service technician can continue to put it in your vehicle, as long as supplies are available. CFC-12 used today is constantly being recovered and recycled, and CFC-12 produced in 1994 and 1995 is being placed into inventory, so that there is still refrigerant available.
7. Can I vent HFC-134a or other refrigerant substitutes?
No. Effective November 15, 1995, section 608 of the Clean Air Act prohibits individuals from knowingly venting substitutes for CFC and HCFC refrigerants during the maintenance, service, repair and disposal of air-conditioning and refrigeration equipment. A fact sheet explains this prohibition in much more detail. Note: although this prohibition is part of Section 608 (stationary refrigeration and air conditioning equipment), it also applies to Section 609 (motor vehicle air conditioning).
8. Is R-134a flammable?
R-134a is not flammable at ambient temperature and atmospheric pressures. However, R-134a service equipment and vehicle a/c systems should not be pressure tested or leak tested with compressed air. Some mixtures of air and R-134a have been shown to be combustible at elevated pressures. These mixtures may be potentially dangerous, causing injury or property damage.
9. Are there any Drop-In Replacement Refrigerants for R-12?
No. A number of refrigerants other than R-134a have been listed by EPA as acceptable under its Significant New Alternatives Policy (SNAP) program, or are under SNAP review. The SNAP program evaluates substitutes only for their effect on human health and the environment, and not for performance or durability. None of these refrigerants have been endorsed by the OEMs for use in vehicles, and few have had extensive testing in a wide range of vehicle models.
While some manufacturers of alternatives may be marketing their products as “drop-ins,” keep in mind that because of the EPA regulations for different service fittings and labeling, there is no such thing as a refrigerant that can literally be dropped in on top of the existing R-12 in the system. Furthermore from a engineering stand point, none of the claimed refrigerants have demonstrated drop-in performance! For more information on the SNAP requirements and on which alternatives have been reviewed, accepted, or deemed unacceptable by EPA, call the EPA Ozone Protection Hotline at (800) 296-1996 and request a copy of “Choosing and Using Alternative Refrigerants in Motor Vehicle Air Conditioning.”
Some people claim that R-134a is only a temporary replacement for R-12, to be used until a drop-in replacement that cools better and does not require a retrofit becomes available. Current research indicates that no such replacement refrigerant exists. The worldwide automotive industry conducted extensive research and testing on many potential substitutes for R-12 before selecting R-134a. This author, the technical community at large, and the EPA are not aware of any plans by the auto makers to use any refrigerant in new vehicles other than R-134a.
10. What refrigerants are used now? What is Freon?
“Freon” is a trade name for CFC and HCFC refrigerants used by DuPont. Other trade names include Allied-Signal’s “Genetron” and ICI’s “Arcton”. Various companies sell the same CFCs, HCFCs, HFCs, and other products under different names. The most common ozone-depleting refrigerants are CFC-12, R-502, and HCFC-22. R-502 is a blend of 48.8% HCFC-22 and 51.2% CFC-115.
11. Should page 67 of the manual say that before you charge a system, you need to use a pressure decay leak test?
The text is correct, essentially always leak check before evacuating, but you are correct in that you also follow evacuation with charging.
To clarify, the procedure prior to charging a system with refrigerant is to:
- Make any necessary repairs
- Pressure test the system for leaks (because a pressure test will always be many times higher pressure differential across the leak, when compared to a vacuum which at best can only have a 14.7 psi pressure differential).
- Once the system is confirmed to be leak free, then evacuate the system to the required level, typically around 500 microns. If you use a vacuum to check for leaks, not only is the pressure differential across the leak much smaller, if there is a leak, you will be drawing air and moisture into the system, making subsequent evacuation far more difficult and potentially contaminating the filter/drier in the system with moisture from the air that leaked into the system.
- Immediately charge the system with refrigerant. Never leave a system sitting in a vacuum. If you can’t charge it immediately, put it under a positive nitrogen pressure or charge it slightly with the proper refrigerant, to bring the system pressure above ambient pressure (above 0 psig).