difference between r12 and r134a expansion valve

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