The chemical composition of R12 and R134a differ. George Brayon Wed August 31, 2005 5:03 PM I believe the optimum supercool setting will vary slightly between an expansion valve for an R12, as compared to R134a, system. This is especially likely on systems with a condenser that is too small for efficient operation with R-134a. ESP when a compressor has frozen. But as there's not a big difference, people say you can suffice with either. Its chemical symbol is CH2FCF3. = R134a Charge Level. Expansion Valve. Then again, there are two different expansion valves. R12 refrigerant required this valve, to maintain the evaporator at a constant or nearly constant pressure, slightly above 36-38 psi to prevent icing. Then, subtract that result by 0.25 pounds to get the proper amount of R134a charge. Only show this user. R134a is called tetrafluoroethane (HFC). Subtract ¼ or 0.25 pounds from this number. As an example, let's say the R12 charge specification is listed at 2 lbs. R-401b is the mixture by weight of 61% R22, 11% R-152a and 28% of R-124. 3) A TXV optimized for 134a will be ok with R12. Oct 31, 2015. Since then, the industry standard has been R134a, which is an efficient replacement. #13. #4. The system has been previously converted to R-134a. 4) Inconsistent Airflow. R134a has a smaller molecule than R12 so R134a will leak out sooner than R12. The general practice of charging the system with 15% less refrigerant adds to the thermal deficiency of R134a. absorb by the evaporator to insure all liquid refrigerant entering the evaporator. During opening or closing . A/C Expansion Valve Replacement Cost. The ratings for evaporator temperatures 40°F, 20°F, -10°F, -40°F in the capacity tables are in accordance with ANSI/ARI The substitute that we used for R-12 was the new HFC called R-134a. You have to replace EVERY O ring including the compressors manifold gasket O ring to the new green color for R134a. R1234yf. The only mechanical differences between an . . I had a 1991 BMW switched to 134a by just changing the low pressure charging valve, flushing and refilling with 134 (maybe with 10% . A. Pressure/temperature plot of R134a vs. R12 is shown in figure 1. What is the refrigerant property involved that has caused this? Joshua, You are correct about the (small) pressure and flow characteristic differences between R-12 and R-134a Expansion valves. Jun 17, 2011. One of the differences between auto air conditioners that have been redesigned from R12 to R134a is that the condensers have gone from serpentine to pseudo-parallel. Bookmarks: Digg; del . The cure is to use the newer R134a compressors is sealing washers that are different thickness. Compared with the cost-performance ratio, R507 is 30-40% . Can I just use an adapter and save $200? 6. The difference really shows up on the high side. Is that why expansion valves are specific to R12 or R134A? They have no moving parts. Take the R12 charge specification and multiply it by 0.9. 12-06-2006, 10:55 PM #4 Andy Schoen Professional Member Join Date Apr 2002 Location Dallas, TX Posts 2,566 Post Likes = R134a Charge Level Rich Membership Chairman The R12 compressor design ports are even. R-134a XV for R-134a use. R134a. According to Wikipedia, There is such a thing as "r132a" (1,1-Dichloro-2,2-Difluoroethane), however there is no indication of it being a commercially produced refrigerant. I would suggest you do stay away from R-134a since with the hot gas bypass of your system (if it is to be just as the original) extremes of temperature and pressure will be very hard on your compressor and the rest of the system. 34 in 70 series w/ R12 in 100+ Tucson, AZ summer heat w/ hd-t, w/ 13B-T is was unbearable about 31 at vent w/ R12. Aug 3, 2018. So, along with R134a came a new oil: Polyalkylene Glycol—or PAG oil. The R134a compressor has a 1/8" step in on the high side port. It won't be optimal, though. R134a has the chemical formula CF3CH2F and is known as tetrafluoroethane. Some say that a chemical reaction can harm the A/C very badly as R134a reacts with mineral oil in some way. GWP is a measurement of Greenhouse Gases and their effect on Global Warming. R404a for freezing of product. In a car ac, using this type of freon 20 years ago was difficult. •Large temperature difference between expansion valve inlet and outlet oReplace expansion valve •Air . As R134A refrigerant has different operating characteristics and pressures this valve is not necesssry. Some 1993 and older R12 systems aren't as 'compatible' as you'd think to switch over. I'm just trying to help you avoid headaches in the long run. The original CFC expansion valve used for R12 needs to be replaced with an HFC one for 134a to feed the evaporator correctly. You can spend long evenings reading about the differences between the two refrigerants. . Also called the orifice tube. Minor adjustments to the expansion valve and other controls may be necessary for some plans. An orifice tube is just a fixed nozzle that pisses refrigerant into the evaporator without any sort of feedback. Its chemical symbol is CCl2F2. . A discussion of the relationship between valve capacities and superheat set-tings can be found in Bulletin 10-9. The crossover point is approximately at 64°F. Make sure to get the R12 EXP valve if that is the way you go. This refers to BTU's (heat) moved per pound of refrigerant moved. Rules governing changing from the former to the latter differ between countries. It was later found that R-134a had a very high Global Warming Potential, or GWP, number. Until 1995, most cars with air conditioning used R-12 Freon refrigerant which has shown to have an environmental impact. 5. Like say half a can or so recharge come springtime warm weather or something. R134a compressors are substituted as new to retrofit the R12 system compressor part numbers with different height sealing washers. Bookmarks: Digg; del . As R134A refrigerant has different operating characteristics and pressures this valve is not necesssry. . . Expansion valves are an active device, they regulate the flow of refrigerant to the evaporator depending on evaporator temperature. Replied by Rich928 on topic R12 or R134a Since the hose is the stock hose, you cannot tell what refrigerant is inside. Expansion Valves Catalog E-1, July 2012. And yes - expansion valves sometimes need replacing if they are sticky - but a proper AC flush should eliminate the need for a new one if it's already in good condition. Thus, when the system is running, condensing the CO2 is not a problem. Judging from the current manufacturer's use results, the R507's effect is indeed faster than the R404A's cooling speed. Anyone know what happens when an R12 expansion valve is used in a system charged with R134A? There are three different refrigerants officially sanctioned by the EPA for automotive usage: r-12, r-. and feeds it through an expansion valve. R-12 "Freon" and 134a. A capacity curve is shown in figure 2 for relative capacity of R134a vs. R12 for evaporating temperatures from 0°F to 50°F. 4) The airflow across the condensor is crucial to good performance. All pre-97 XJs use systems with the same basic operating principle, although the parts do change a bit. R134a compressors are built to run a higher head pressure (R134a has a higher working pressure than R12) and the lubricants are incompatible. R134a systems operate at higher discharge-side pressures than R12, which can cause compressor seals to leak. Recommendations From A/C Shops and Aftermarket: Lower the adjustment of the clutch cycling switch to 21 to 22 PSI. The cure is to use the newer R134a compressors is sealing washers that are different thickness. Answer: OK, I'll bite. Can I use the one for the R-12? Some vehicles' older hoses will allow the R134 refrigerant to 'seep' through the linings on the hoses. The Wikipedia explanation for expansions valves cited in Frank's thread says that the gas inside the bulb in the metering valve is the same as the refrigerant in the system. . You will be fine with a 134a-compatible TXV running R12. A. Pressure/temperature table for R12, R134a, and R513A is shown in Figure 1. . You will be fine with a 134a-compatible TXV running R12. The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman. To ensure the right charge, you must fill the new system with between 75 and 85% of the factory-set capacity for optimal cooling. The adjusted tension of this spring is the determining factor in the opening and closing of the expansion valve. Jun 19, 2007. Operating Pressure/Temperature Differences The pressure/temperature curves for R-1234yf and R-134a are very similar. R12 and R22 are both now banned by the EPA in the United States. R134a for cooling of product. It is good replacement for R12 in the applications where the evaporator temperature is -23 degree C and above. Thus, when the system is running, condensing the CO2 is not a problem. maintain the A/C of older cars. and an evaporator core and expansion valve that are optimized for R134a . Formula: (R12 Charge Specification x 0.9) - 0.25 lbs. and he synthesized R-134a in 1936, 5 years after R-12 was . R134a requires the use of synthetic oil! In 1994 they switched from R-12 to R-134a. R134a is roughly 9$ per lb. It is good replacement for R12 in the applications where the evaporator temperature is -23 degree C and above. R12 Expansion Valve = 201 830 06 84 R134A Expansion Valve = 201 830 04 84 Is there a difference after all? This is the part that controls the system pressures. You would do the following: This indicates that an . You may need to adjust the valve in a bit to get desired superheat. Also, this will give you the opportunity to replace all the evaporator seals which are recommended to be done in a conversion. This is due to many facts: R134a refrigerant is about 10% less efficient in moving heat than R12! Is the information not applicable to the old Pantera system? I recommend replacing the expansion valve when you do the swap. R12 is heavier than R134a and has smaller molecules. 1) Warm Air From Vents. And with R134a costing only two bucks a can, converting to the new inexpensive refrigerant seemed the thing ELECTRONIC EXPANSION VALVES: High Efficiency … The GWP value of the refrigerant used is 1.430 (refrigerant type R134a). Catalog E-1, Thermostatic & Automatic Expansion Valves / Page 1 Table of Contents . turns into a vapor before it exits. The good thing is that after you convert to R134 you can top off the system easily and cheaply. Also, the 93 part numbers note R12, the 94 parts note R134. It's best to determine on a case-by-case basis while monitoring system pressures and output air temperature. What's the difference between R12 and R134? yes R1234yf Freon gas can be replaced by R134a; the newer systems were designed with this in mind so no, there will be no damage to the compressor but some time in . The general practice of charging the system with 15% less refrigerant adds to the thermal deficiency of R134a. Later model cars that come with 134A will have 134A only connectors. 3) A/C Compressor Always On. This works when the R12 charge specification is listed in pounds. Originally Posted by goldNSX. So you could likely put off buying those new hoses just a bit longer if you wanted. One of the differences between auto air conditioners that have been redesigned from R12 to R134a is that the condensers have gone from serpentine to pseudo-parallel. The difference really shows up on the high side. In the automotive world, the replacement for R12 was R134a. Given their small cost, R-134a has a greater net refrigerating effect than R-12 which causes the valve capacity to increase. One of the differences between auto air conditioners that have been redesigned from R12 to R134a is that the condensers have gone from serpentine to pseudo-parallel. According to the thermodynamic characteristics, it is close to the R12 freon, however, it is 10-15% worse in terms of cooling capacity and is more fluid. That is for the compressor, drier, expansion valve and condenser. A final difference is that most (though not all) R-1234yf cars will have a Suction Line Heat Exchanger. Differences between R-12 and R-134a systems: 1. 4.R404A R134a increased mass transfer resistance to reduce the transmission chamber heat coefficient, while R507 heat transfer coefficient is higher than R404A. You'll get marginally better performance out of the change as the expansion valve is matches the refrigerant characteristics. To discover the capacity for refrigerant, you want to use the specs for the current system and multiply the R12 charge by 0.9 or 90%. The expansion valve is designed so that the temperature of the refrigerant at the evaporator outlet must have 8 to 12°F (4 to 7°C) of superheat before more refrigerant is allowed to enter the evaporator. For example, at an evap temp of 30° (your daughter's system is probably running around 25°-28° saturated in order to give a 32° duct temp), the pressure of R-134a is 26.1psi. 2) Frost on the Vents. Then, subtract that result by 0.25 pounds to get the proper amount of R134a charge. 37 in 2005 tacoma, R134A. Bottom line, R134a simply doesn't cool as well as R12. R134a refrigerant is lighter than R12. However the real limiter on the conversion is the condenser. With new R12 no longer being manufactured, the market price soared to $100/pound. Answer (1 of 10): According to this article, Real World Experience with R1234yf: The New Refrigerant is Finally Here; Are You Ready? . All fans must work at 100% of the OEM rating. Are r12 and r134 fittings different? temps should be measured 1" from vent. A slow loss of cooling at city speeds is usually related to condensor capacity & airflow issues. R134a refrigerant is about 10% less efficient in moving heat than R12! _____ 2012 E350 2006 Callaway SC560 . The pressure at low temperatures is nearly the same between 12 and 134a. The difference between R12 and R134a TEV (exp valves) is primarily the 'superheat'. They plug all the time. -The amount of R-134a needed will typically be 80-90% of the R-12 charge. You can use any gauges you like to check the pressure of the system, with slight risk of cross contamination. 03-15-2006, 06:29 AM #5. dixie2005. Mark Baker R12, on the other hand, is called chlorofluorocarbon (CFC). (On firewall where A/C lines go into cab.) R-12 - yellow R-134a - light blue R-22 - green R-402A - light brown (sand) R-402B - olive R-404A - orange R-407C - medium brown R-410A - rose R-507 - teal J Even if the system leaks, repairing the leaks and recharging it with R-12 is usually the best repair alternative. CLUTCH CYCLING SWITCH. R404a is a zeotropic blend with a temp glide , because of the mixture of 2 or more refrigerants. The Main change in the system is the expansion valve. First, differences in physical properties: 1, insoluble R12 compressor oil is used (to reduce the lubricant) 2, dissolved sealing materials are used (resulting in refrigerant leakage) 3, easy to damp (so easy to internal . It can be used applications like walk-in coolers, food and dairy display cases, domestic refrigerators, and beverage dispensers and vending machines. Using R134a in an R12 system will cause the oil not to move with the refrigerant, causing a system failure and probably won't even cool the system well, if at all. Compressor. The expansion valve(Tx) is in the car at the inlet line to the evaporator with compressors you best get advice from an ac specialist shop as the differences could be the gas that it pumps some systems use R12 and others use R134a or later gas 05-25-2017 02:14 AM. The symbol implies that R12 is a composite of carbon, chlorine, and fluorine. With R-12, 30° is 28.4psi and 40° is 36.9psi, for a difference of 8.5psi. The difference between R12 and r134a is the BTU carrying capability. … R12 systems used mineral oil, but unfortunately mineral oil doesn't dissolve in R134a. If you're getting a R134a compressor, might as well finish the job - replace the receiver/dryer, flush everything else, and convert to R134a anyhow. sparkee said: Thanks for the Service Bulletin. However, it was found to be a very bad gas for the environment. Bad Car A/C Expansion Valve Symptoms. This refers to BTU's (heat) moved per pound of refrigerant moved. _____ 2012 E350 2006 Callaway SC560 . Take the R12 charge specification and multiply it by 0.9. Although the compressors are different the SD709 R-12 compressor can use R-134a, . Some vehicles won't be a concern. Yes, you can accidently fill a converted R134a system with R12, only if they left the R12 fittings fittings. Formula: (R12 Charge Specification x 0.9) - 0.25 lbs. Also the new quick connect fittings for the high & low side. Assuming that the systems have been completely flushed and the appropriate oils are used, putting R12 in an R134a system will result in: - Longer system life (R12 carries lubrication oil better than R134a) - Lower system pressures (also contributes to longer life) - Superior cooling. R-12 expansion valves can be re-used, but will not be as efficient as R-134a specific ones because of the slightly different pressure specs of R-12 vs. R-134a. There are two hoses listed, R-12 64-53-1-377-821 for $72.50, and R-134a 64-53-8-391-051 fro $262.50. It's actually a reaction with chlorine in the mineral oil that may have been absorbed and leftover from the old R-12. Above this temperature, the saturation pressure of R134a is higher than that of R12; below, it is lower. If the system was upgraded by a professional it should have an upgrade sticker. The differences in P e between the HR12 and R134a in the MAC at a T oa of 30, 35, and 40 °C were -41.47%, -38.67%, and 12.02%, respectively. ing the expansion valve, a maximum opening superheat of 7°F, and a standard factory air test superheat setting. There is NO reason to retrofit a vehicle to R-134a as long as the R-12 system is cooling properly and contains a normal charge of refrigerant. How an A/C Expansion Valve Works. R12 and R134 are of different chemistry. You'll want the expansion valve matched to whatever refrigerant you're using. -The cooling may not be as good as with R-12. R-134A has a slightly lower pressure at evaporator temperatures (30-40 degrees), but R-134a also has a much higher pressure at condenser temperatures (120-150 degrees). A lower GWP alternative to R-134a had to be found and thus we have the new 1234yf. R134a compressors are substituted as new to retrofit the R12 system compressor part numbers with different height sealing washers. The R134a compressor has a 1/8" step in on the high side port. R12 can move more heat than r134 so when it isn't very hot and the system isn't maxed out you wont be able to tell the difference but when its 110 out and the inside is 140 R12 will cool the cabin temp faster. . You can use the R134a retrofit capacity chart for this purpose. It can be used applications like walk-in coolers, food and dairy display cases, domestic refrigerators, and beverage dispensers and vending machines. But R22 is almost equally damaging. James10952001. Generally, the new amount is 75-85% of the quantity advised by the manufacturer. This is because the pressure temperature relationship of R-12 and R-134a is different. R-401b is the mixture by weight of 61% R22, 11% R-152a and 28% of R-124. 5) A/C System Failure. Comparatively, larger R134a molecules should take more space, and a smaller amount might be required. Today it is often used in refrigeration equipment. #19. might be due to charge or different compressor and age. When I compare parts, 93 uses one part number and 94 has a different part number. R134 tends to "seep" from older hoses a bit more than R12. The R12 compressor design ports are even. R12 was once used in many air conditioning units as a refrigerant or cooling agent. and he synthesized R-134a in 1936, 5 years after R-12 was . For instance at 25 °F the pressure of R-12 is 24.6 PSI and the pressure of R-134a is 22.1 PSI. So if you car has a large amount of rubber hose, such as a 40 feet with the 911, then you will be re-charging the system often and that is expensive no matter which refrigerant you use. In an AC system, the oil is constantly moving with the refrigerant. ebyrd10000 March 6th, 2008, 16:30 "Howdy, Folks!" The pressure at low temperatures is nearly the same between 12 and 134a. That would be the "black death" syndrome. At 40°, it is 35psi, which is a difference of 8.9psi. and feeds it through an expansion valve. There is a lot of differences between the R12 and the R134a fittings, you can't mistake them. Superheat you can consider to be the additional amount of heat. The difference between R12 and R134A systems compared with the R12 R134a have different physical and chemical properties. 42 (at best) w/ 134A in 2000 isuzu trooper. R12 Expansion Valve = 201 830 06 84 R134A Expansion Valve = 201 830 04 84 Is there a difference after all? I dont know why the cost difference between compressors is so huge, though. B. If not, you just don't know unless a test is performed. The only difference I can imagine would be the recharge connection. There are significant differences between R12, R134a, and R513A, which must be considered when handling, processing, applying, or retrofitting with these refrigerants. If liquid refrigerant were to exit the evaporator. leading to corrosion of expansion valves, capillary tube plugging, and compressor bearing . A/C systems designed to use R-12 will cool best when charged with R-12 refrigerant. Since there is only about a 10% difference between R-12 and R-134a, the expansion valve being self-compensating really doesn't make that much difference. How is 1234yf different from . The only material difference between automotive A/C and a window A/C unit or refrigerator is that in the home application, the components are all inside the same rectangular box, but in the automotive application, the components are distributed throughout the car. The P H and T cond,sat of the HR12 at a T oa of 40 °C were higher than that of the R134a, resulting in a higher P e than that for the R134a. R-12 is no longer used or produced in many countries and remaining quantities have skyrocketed in price. R-134a is widely believed to be the most acceptable R12 substitute. Production of R12 ceased in 1996, although it can still be reclaimed, purified, and resold, and small cans of New Old Stock R12 are still widely available on eBay and Craigslist. This part is part of the line assembly and is designed to improve efficiency. It is made up of carbon, hydrogen, and fluorine. In automotive air conditioning systems, refrigerants R12 and .

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