I don't have the FSM matrix handy for that 123.123, but a 123.133 shows a test rpm of 2,000 - and vent temps between 54f & 66f at 91f to 95f ambient. Then again, there are two different expansion valves. What is a good differential? I recommend replacing the expansion valve when you do the swap. Bottom line, R134a simply doesn't cool as well as R12. Hopefully after you have read this entire page you will have enough information to determine which type of refrigerant is best for you. That is a good thing. CONCLUSIONS The differences in the theoretical C.O.P.H calculated for R12 and R134a are consistent with values quoted in the literature. Is there a difference between a R134a expansion valve and an R12 TXV? 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. There is a lot of differences between the R12 and the R134a fittings, you can't mistake them. Besides, its technology has been tested and trusted. Later model cars that come with 134A will have 134A only connectors. By using a qualified a/c shop with the proper equipment you odds are in your favor of having the job done correctly the first time. Use a drop light in the engine bay, and check the air path from the front of the car at night. And by matching the correct amount of R134a to use in a given vehicle, correcting the superheat of the expansion valve (if necessary), you can in some manner nearly balance or match the amount of heat drawn out by the evaporator and released by the condenser. . Using R134a requires that Polyolester (POE) lubricant must be used in the compressor. A/C receiver difference between R12 and R134a? Have a look in the FAQ Section, and look for "Fan clutches & testing them". If ambient is 90 (today) and the output of the condensor is 110, that's pretty good isn't it? If you have the work done, be sure you find a true "A/C" shop that can make up lines. The problem with not being an expert is that you don't know what is important and what's not. How an A/C Expansion Valve Works. You either get a system that will function well with R1234yf or get any other type. R12 was once used in many air conditioning units as a refrigerant or cooling agent. Any advice appreciated. Minor adjustments to the expansion valve and other controls may be necessary for some plans. The only difference I can imagine would be the recharge connection. This can be very very expensive. I bought a relay to put on it connected to the compressor clutch. Further production of R12 was banned in some developed countries by the Montreal Protocol because of its harsh effect on the ozone layer. Before R12 was replaced with R134a in 1995, it was mostly used in trucks and cars. I think the way to go here is1. The oil used in R12 systems is not compatible with R134a refrigerant. Is there a graph? 3) A/C Compressor Always On. That would be the "black death" syndrome. When you add fluorescent tracer dye to with the refrigerant oil it helps to track down leaks that push oil out of the system. We've updated our forums!Click here to visit the new forum, Year: 1983Make: MercedesModel: 240DEngine Size: 2.4Refrigerant Type: R12Ambient Temp: 90Pressure Low: 35Pressure High: ?Country of Origin: United States, Hi, this is my first post, so please take it easy on the noob. But, if your car lacks enough condenser and you have many 100+ degree days then you may want to stick either increase air flow, add another condenser as we mentioned in The Mr. Ice Project or stick with R12. Besides R134a there are some other refrigerants that are approved to replace R12 and there is a long list of refrigerants that are not approved. This would become an expensive investment for a repair or service station to have unique dedicated equipment for every type of alternative refrigerant. Hot coolant migrates up through the core by convection (is that the word? I have a laser temp reader, and it says the temps going into the condensor are up to 160F - coming out it is always around 110 or so. R134a has the chemical formula CF3CH2F and is known as tetrafluoroethane. It's best to determine on a case-by-case basis while monitoring system pressures and output air temperature. It runs between the condenser outlet, receiver/drier unit and expansion valve at the firewall. They would then make short "jumper hoses" to connect to the existing stock hoses, refit your old fan if there is a "pusher" fan, and recharge to specs. Also the new quick connect fittings for the high & low side. Jun 19, 2007. Discussion in 'Technical' started by Jsarnold, May 25, 2012. -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a, Hi pdrayton- If you can remember the oil capacity that you found in all your research and post that, then bohica and others can have a better idea if you have too much; see if you can find that info! A/C systems designed to use R-12 will cool best when charged with R-12 refrigerant. The higher the ambient temperature the higher the high side pressure. The general practice of charging the system with 15% less refrigerant adds to the thermal deficiency of R134a. Vent temperatures slowly go down to around 50F with hi speed driving. -------------------------"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest." With new R12 no longer being manufactured, the market price soared to $100/pound. If the system was upgraded by a professional it should have an upgrade sticker. Do a pre-inspection and then Evacuate (vacuum down) the system, the longer the evacuation the better but there is a point of diminishing return, 2-3 hours is generally very good. A. Pressure/temperature table for R12, R134a, and R513A is shown in Figure 1. . . 4.3 out of 5 stars 491. Generally the system will be initially charged with approximately 80% to 85% of the original amount of R12, using R134a. R404a for freezing of product. I had to vaccum the system for 2 hours and recharge 4 oz of PAG oil plus 36 oz of 134A freon (3 cans). The smoking question & vent airflow indicate that the evaporator is fairly clean - and you are aware of the importance of that.The heater valve stops the flow, but there is always some conduction heating. Thus, when the system is running, condensing the CO2 is not a problem. difference between r12 and r134a expansion valve . The global warming potential measures the amount of heat trapped by any gas compared to the amount of heat trapped by the same amount of carbon dioxide. So you could likely put off buying those new hoses just a bit longer if you wanted. If you you dont have the free time to play then you are better off to pay a technician. By after changing just about everything, he got what was termed, satisfactory cooling. don't know enough about the subject to explain the choices.However, a few days ago I called the dealer to see about an OEM TEV and they said something that made me feel a little bit better; the same part number superceded every application back to the '60s, and that they couldn't do that without engineering signing off on it.Still, I would feel a lot better if I could see something written officially that compared the flow characteristics and performance of r12 and 134a TEVs are concluded that they were interchangeable in automotive applications.If someone knows of such a document I would sleep much better!Walt Edited: Mon September 12, 2005 at 8:13 PM by wamcneil. Use a strong surfactant like Simple Green or Zep Citrus, and soak the fins on the condensor. It was later found that R-134a had a very high Global Warming Potential, or GWP, number. I'll put the relay on for that. I used a full can of evap cleaner. R134a compressors are substituted as new to retrofit the R12 system compressor part numbers with different height sealing washers. compressor, condenser, evaporator and expansion valve are specifically designed for use with R134a. I don't want to be chasing ghosts. However, it was found to be a very bad gas for the environment. I'm thinking I might have put too much oil in the system - everywhere i read had a different amount - the manufacturer of the compressor, the MB factory service manual, online forums. ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. 4.R404A R134a increased mass transfer resistance to reduce the transmission chamber heat coefficient, while R507 heat transfer coefficient is higher than R404A. It won't be optimal, though. Or is there always room for improvement, the more the merrier. By noting the ambient temperature you can look up what the preferred high side pressure should be. Also, would a genuine R12 TXV be better, or is it too marginal to worry about?I think I should do the FSM test for performance - they have a graph with ambient temp and a/c temp. Do I leave the orignal condensor in, etc?Thanks. Also, R134a cylinders are light-blue in color. Just leave it alone for now. You can also check the Aux fan in your case. All fans must work at 100% of the OEM rating. Expansion Valve. A/C Expansion Valve Replacement Cost. Looks like a couple of things happening here1) 80's vintage Eurocars were not "meat lockers". I don't think it has any air dams or seals, I'll check to make sure. The mechanical fan & clutch should be checked as well. The larger line at the expansion valve is the suction line. This is because R134a. might be due to charge or different compressor and age. However, theyre still used in older plants, systems, and the automotive industry. R12 is simply too expensive for a 25+ year old A/C system. 5. Spray it deep, and let it sit for a few minutes. The butylcellusolve or the citrus solvent will dissolve the carcass in a few minutes. Is checking the temperature of the in and out of the condensor not the easiest way to tell if it is doing a good job or not? Inasmuch as R134a has a global warming potential thats over 1000 times more threatening than carbon dioxide, its better than R12. Make sure to wear safety gloves, goggles, and shoes when theres a possibility of exposure to the chemical (R134a). R134a refrigerant is lighter than R12. I'm doing one thing at a time so I know what the cause was. a 50f delta across the condensor is good, but I suspect that is an idle reading. Compatible with multiple applications: The major reason for the introduction of R134a was to replace R12, so it functions perfectly in the same range of applications like rotary, screw, and centrifugal compressors for air conditioning and refrigeration. 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. R12 systems used mineral oil, but unfortunately mineral oil doesn't dissolve in R134a. You will be fine with a 134a-compatible TXV running R12. But some types of PAG do not mix well with the old residual R12 mineral oil left in the system components whereas ester does mix very well. . -------------------------"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest." Depending on which circuit diagram fits your car (cough, no vin list exists) you have either one or two switches controlling the aux fan. Refrigerators generally utilize R22, R32, or 410A-based coolants as their cooling agent. bokoen1 hoi4 the great purge / meryl and maks dancing with the stars / difference between r12 and r134a expansion valve. It cycles on off in med (or low for that matter)Gotta tell ya. Some compressor manufacturers or OEMs suggest PAG type oil for R134a. A final difference is that most (though not all) R-1234yf cars will have a Suction Line Heat Exchanger. R134a is called tetrafluoroethane (HFC). Your average garage that works on a/c on the side probably would not have this. I'm putting r12 back in my system, but all of the valves I can for the application (1990 jeep grand wagoneer) say r134a on them. You can buy bulk hose, and the proper fittings, then have them crimped off the vehicle.Be sure that no air bypasses the new condensor on the way to the radiator. Can I order a valve based on the original eaton number? Also called the orifice tube. You should keep in mind that recharging your air conditioner improperly could result in more serious damage. Low refrigerating effect per pound: In comparison to other refrigerants, the refrigerating effect of R12 per pound is low. GWP is a measurement of Greenhouse Gases and their effect on Global Warming. -------------------------Just another brick in the wallHad a little mule I fed him castor oil and every time he jumped the fence he fertilized the soil, The older expansion valves were filled with the refrigerant they were used with, the replacement valves (today) are filled with a different chemical to work with both refrigerants..Hope this helps-------------------------ChickEmail: Chick---------------------------------------------Freedoms just another word for nothing left to lose, I believe the optimum supercool setting will vary slightly between an expansion valve for an R12, as compared to R134a, system. As noted, measure up front as best as you can to get as close to the aftermarket dim. There are significant differences between R12, R134a, and R513A, which must be considered when handling, processing, applying, or retrofitting with these refrigerants. Energy usage: R134a is less efficient in cooling compared to R12. The R134a compressor has a 1/8" step in on the high side port. 5) A/C System Failure. Expansion valves are an active device, they regulate the flow of refrigerant to the evaporator depending on evaporator temperature. Participate in over 40 different forums and search/browse from nearly 3 million posts. MB has specfic test parameters for performance, but you can always test at max load - doors open fan on highest speed.The oil overcharge looks like a parabolic curve. George Bray on 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. Get to the point where I can walk without crutches2. "Jerky Locker" LMAO I am using that one in the future!Florida = BUGS! With R12 you use to check to see if the site glass was full, if it had bubbles it meant you had a low charge. 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. Disconnect the two hose lines to the compressor, protect the ends from getting dirty. Some say that a chemical reaction can harm the A/C very badly as R134a reacts with mineral oil in some way. From memory, I put in at least 8 ounces of oil, probably around 10 ounces in there. Replied by Rich928 on topic R12 or R134a. RULES for AOP - Owner Assistance and Contractors, Energy Efficiency and Building Performance Discussion NEW, Carnak Zone/Locked Areas - For Professional Member Only, How To Become a Pro and Rules For Pro Members, Pro Forum: Refrigerants and EPA regulations **NEW, Pro Forum: Residential Refrigeration and Appliances **NEW, Pro Forum: Equipment Recalls and Bulletins **NEW, Pro's Forum: Building Science Discussions, Educational Forums - Open for all in the industry, Welcome to HVAC-Talk's Educational Forums, How to Submit Links, Articles and Quiz Questions, Frequently Asked Questions About Submissions, Physics, Thermodynamics, Fluid Flow and Combustion, Educational, Training & Reference Information, Manufacturer's Technical Information Links, Electrical Theory, Circuits and Electronics, HVACR Equipment, Components & Accessories, Accessories Humidifiers, Air Cleaners, HRUs, Fans, Filters, etc. R12 is used in several applications like low temperature, medium temperature, and high-temperature applications. What was the ambient when you took that reading?Jumpering the aux fan is a common thing here in the desert. Stability: RR12 doesnt disintegrate even under extreme operating conditions. I'm not sure. I just got some hi/lo side gauges so I'm going to take readings, if they are needed. 3) A TXV optimized for 134a will be ok with R12. 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. Its chemical symbol is CH2FCF3. ESP when a compressor has frozen. R134a is otherwise called 1,1,1,2 Tetrafluoroethane, Florasol 134a, Freon 134a, Norflurane (INN) or HFC 134a. PaulJerky King -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a. Some 1993 and older R12 systems aren't as 'compatible' as you'd think to switch over. And, unfortunately a small high side pressure gauge on a short hose. For instance you can evacuate FRIGC FR-12 into a refrigerant recovery bottle that has R134a in it or visa versa. It is also used in automotive car conditioning and the plastic industry. R134a systems operate at higher discharge-side pressures than R12, which can cause compressor seals to leak. Whether R134a performs as well as R12 in any given a/c system depends upon system components and the amount of R134a used. . However, R134a is better than R12. Even with proper fan operation, missing seals & air dams can effect condensor effeciency. Post photos, respond to polls and access other special features. leading to corrosion of expansion valves, capillary tube plugging, and compressor bearing . 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. Any ideas from the info above? R12, on the other hand, has an ozone depletion potential of 1, implying that it can damage the ozone layer. Jun 17, 2011. . Most importantly, the oil used in the plant must always be compatible with the refrigerant used. Nevertheless, if your application is configured only for R12, then you can use it or consider replacing the applications engine. Bohica, I appreciate your help with this. $21 . In this study, without the need for major modifications to the bus air conditioner, the variation of the ejector dimensions according to different parameters has been investigated in the case of using the R1234yf, R1234ze(E), or R600a refrigerants, which may be a substitute for R134a as a refrigerant due to . Moreso, it had been banned. Stay home and grill your own steaks and stir your own martini. You may have heard of a friend that did the job himself with borrowed equipment and 12 or 16 ounce cans of refrigerant. I'm going to check the condensor is way clean too. R1234yf is more environmentally friendly and has a global warming potential of 4.
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