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