Edited: Sat July 14, 2007 at 10:22 PM by fonebone. R134a refrigerant is about 10% less efficient in moving heat than R12! Use a strong surfactant like Simple Green or Zep Citrus, and soak the fins on the condensor. B. Therefore, its most suitable for both commercial and domestic environments. R134a requires a different oil. We recently created this blog site to enable us to share our knowledge with other automotive mechanics and car owners. The higher the ambient temperature the higher the high side pressure. R12 is CFC: Even though R12 is one of the most commonly used refrigerants, it is CFC. If 50 degrees across the cond. However, take note that R134a refrigerants are manufactured specifically for automotive air conditioners. Formula: (R12 Charge Specification x 0.9) - 0.25 lbs. It was later found that R-134a had a very high Global Warming Potential, or GWP, number. There are significant differences between R12, R134a, and R513A, which must be considered when handling, processing, applying, or retrofitting with these refrigerants. R134a compressors are substituted as new to retrofit the R12 system compressor part numbers with different height sealing washers. Below are the major differences between R134a and R12: Chemistry The chemical composition of R12 and R134a differ. Carefully study the chart and compare the following: To a large extent, the choice is up to you. had writing on the side that said R134a. You can use this space to go into a little more detail about your company. In practice this means that the car can overheat and the aux fan will stay off! It is perhaps possible to locate a unit with a company that purchases close out or distressed merchandise. Plus, not releasing the chemical into the air is morally justifiable. Trinary Pressure Switch quantity. It is mixed with the freon for the most part, and does accumulate in all components in small amounts. The larger fitting goes on the discharge port and the smaller fitting goes on the suction line or compressor inlet / suction port. Minor adjustments to the expansion valve and other controls may be necessary for some plans. Are you sure you have an R4? Interestingly, theres one oil type that works perfectly with both types of refrigerants. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyers guides, and car and tools comparisons. If there is no pusher fan, and you have the room, put one in. How an A/C Expansion Valve Works. 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. Anyone know what happens when an R12 expansion valve is used in a system charged with R134A? Shorting the plug for the refrigerant switch should run the fan when the compressor is on. With that said, I would source the TXV from another source such as NAPA just to avoid any problems. Your decision could be made based on economics, environmental concerns, or both. The difference between R12 and r134a is the BTU carrying capability. 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. Nick, I hear you - there maybe nothing to do here. Don't like the sound of custom parallel condensor. A. Pressure/temperature table for R12, R134a, and R513A is shown in Figure 1. . The adjusted tension of this spring is the determining factor in the opening and closing of the expansion valve. The only mechanical differences between an R12 system and an R134a system are that R134a systems typically have larger condensers and more powerful compressors. That would be the "black death" syndrome. ThanksPaul -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a. With the knowledge of the differences, youll be able to draw a comparison between R12 vs R134a efficiency. The mechanical fan & clutch should be checked as well. I put in a new (not reman) compressor (R4 I believe it is) in my merc 240D, new drier, new expansion valve, new o-rings, nylog. They can be mounted quite easy,and there is a mounting kit that helps to hang it. Thread starter goldNSX; Start date 1 August 2009; Tagged . Existing technology: R134a has been in use in the refrigeration industry for very many years, and theres so much information about the safe use of the product. R12 and R22 are both now banned by the EPA in the United States. I am ordering new parts, and planning to convert my system to R-134a. However, R134a is better than R12. So that indicates it is cooling well there doesn't it? It won't be optimal, though. leading to corrosion of expansion valves, capillary tube plugging, and compressor bearing . 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. "Howdy, Folks!" It is common for eurocar threads to go multiple pages, and as Nick points out - sometimes cool is all you will ever get. It won't be optimal, though. R12, on the other hand, is called chlorofluorocarbon (CFC). 5. Since then, the industry standard has been R134a, which is an efficient replacement. However, theyre still used in older plants, systems, and the automotive industry. Above this temperature, the saturation pressure of R134a is higher than that of R12; below, it is lower. Hence, the effect of R12 on global warming is up to 10,000 times higher than carbon dioxide. Stay home and grill your own steaks and stir your own martini. Right now you know you have a bit too much, but with a CR4P compressor this is an insurance policy. There are other refrigerants: some of which may work, some of which dont work, some of which will destroy your a/c system and some of which are dangerous. Your average garage that works on a/c on the side probably would not have this. Do I leave the orignal condensor in, etc?Thanks. Pray I can let some oil out of the compressor without losing my precious R12. This drop can affect energy consumption since the plant will operate for a longer period or a larger plant will have to be installed. I bought a relay to put on it connected to the compressor clutch. 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 . R-134a is widely believed to be the most acceptable R12 substitute. The cure is to use the newer R134a compressors is sealing washers that are different thickness. The bad thing is I don't know what to do about it. If the system was upgraded by a professional it should have an upgrade sticker. I don't recall all the details, but starts off with the largest parallel flow condenser and improved fans. Its duty is to convert toxic gasses produced by the engine into A brake cleaner is a powerful solvent for cleaning dirt from the brakes and other car components. The analysis focuses on Coefficient of Performance for . Please enter a password for your user account. At this time you can still find R12, but, because it is no longer produced, availability is limited to current inventories and the price per pound is greater than R134a. As R134A refrigerant has different operating characteristics and pressures this valve is not necesssry. This leads me to labor over every small decision. Post photos, respond to polls and access other special features. As for R134a and R1234yf, theres no room for conversion. And, unfortunately a small high side pressure gauge on a short hose. 37 in 2005 tacoma, R134A. It is possible I have 10 ounces (250 ml) in the system. Additionally, R134a was introduced as a replacement for R22 and R12 in high and medium-temperature refrigeration systems like domestic and commercial chillers. 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. But as there's not a big difference, people say you can suffice with either. Lets take you through the advantages, disadvantages, and differences of these two refrigerants a detailed comparison including R12 vs R134a performance. In short, NO! 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. The R134a compressor has a 1/8" step in on the high side port. The condenser water inlet temperature and flow rate are controlled with the use of a . And no, you cannot "drain' excess oil out. Different correction factors are applied to other refrigerants. In large application systems, the vapor density of this refrigerant is usually high. The money you will save by will pay for the R12. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. A discussion of the relationship between valve capacities and superheat set-tings can be found in Bulletin 10-9. 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 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 experimental values of C.O.P.H obtained with the R134a/ester charge were 20.2% The substitute that we used for R-12 was the new HFC called R-134a. . I could easily be over at least 2 - 3 ounces over on the oil. By using a black light the dye will glow in areas where oil leaks are visible. -------------------------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! So to keep things simple and to avoid controversy and politics we have R134a. For instance at 25 F the pressure of R-12 is 24.6 PSI and the pressure of R-134a is 22.1 PSI. Is there a difference between a R134a expansion valve and an R12 TXV? R1234yf is more environmentally friendly and has a global warming potential of 4. Look at where the lines will end up. A comparison between R12 vs. R134a temperature will show that R12 has a higher temperature than R134a. From memory, I put in at least 8 ounces of oil, probably around 10 ounces in there. The system will be checked for gross leaks while under vacuum. Have a look in the FAQ Section, and look for "Fan clutches & testing them". The cost of recharging the air conditioner is between $150 to $500. Big . The pressure/temperature curves for R-1234yf and R-134a are very similar. This is a great space to write long text about your company and your services. What is needed? It is made up of carbon, hydrogen, and fluorine. I'm doing one thing at a time so I know what the cause was. 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 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? At 2000rpm, windows open, highest fan, hi pressure stabilized at 225 psi, low 25psi.Ambient 81F, vent 61F. . This means that it has a high potential of causing depletion to the ozone layer. 1) Look Here at the available sizes of PF condensors.2) Go look at your vehicle's condensor & mounting. You do not need to replace the expansion valve in most cases. 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. Is it exponential, squared? Besides, its technology has been tested and trusted. They might say for instance, add 3-4 oz of oil to the compressor, 1 oz of oil for when you replace a drier, 2 oz oil for the evaporator and so on. Crap! The value of carbon dioxide is 1. and feeds it through an expansion valve. Very nice! 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. I have the original (R12) style expansion valve in the Maverick AC system. 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. Expansion Valves Catalog E-1, July 2012. It will work and there will be very little, in any difference in performance.As Chick stated, the difference is only the gas used in the sensor tube. (The .133 is the 300D Turbo).So, what does your compressor look like?B. Replacement expansion valve for R134a or R12 A/C refrigerants, with O-ring connections. Rules governing changing from the former to the latter differ between countries. 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 only difference I can imagine would be the recharge connection. Inhalation of vapor: Inhaling a large amount of R134a vapor can lead to drowsiness, temporary nervous system depression, and lethargy. A vacuum pump, a refrigerant recover system, quality service gauge set with both low and high side gagues, and much more besides the lessons to learn what to do and what not to do. Rules governing changing from the former to the latter differ between countries. This may be the source of your oil confusion. Read on for more information about using automotive r134a in a refrigerator and vice versa. Flush with a garden hose - do not use a high pressure washer - you can bend the fins flat & damage the condensor.B. This refers to BTU's (heat) moved per pound of refrigerant moved. Remove the old mineral oil from the compressor by turning it upside down, side to side, and turn the front hub on the clutch assembly. Are r12 and r134 fittings different? ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. Its chemical symbol is CCl2F2. Its chemical symbol is CCl2F2. An extra half ounce? The non-flammables can have R22 type gas which is not compatible with most rubber hoses or they have gases that contribute to global warming. Hence, let us continue to fix it. You will be fine with a 134a-compatible TXV running R12. Moreso, it had been banned. Put a relay on the compressor clutch to the aux fan (I like that idea - makes a lot of sense)How does that sound? difference between r12 and r134a expansion valve. R134a requires the use of synthetic oil! It has already been clearly stated that R12 is a chemical that damages the earths ozone layer and shouldnt be released into the environment no matter the circumstance. R12 is simply too expensive for a 25+ year old A/C system. Should I do the test again with the the aux fan jumpered? 05-25-2017 02:14 AM. R12, on the other hand, is called chlorofluorocarbon (CFC). It's not just the poor performance - the cooling just stops working after a while. R-134a XV for R-134a use. How about evacing 1 pound of refrig from the system, and then putting 1 lb of pure R12 back in? R12 systems used mineral oil, but unfortunately mineral oil doesn't dissolve in R134a. As per their results . The flammables have hydrocarbons. 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.
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