difference between r12 and r134a expansion valve

However, take note that R134a refrigerants are manufactured specifically for automotive air conditioners. Bohica, I appreciate your help with this. and feeds it through an expansion valve. The OEM spec is 2300 rpm @ 12.6v (engine stopped fully charged battery). Jun 19, 2007. I cleaned the evap as best I could, if that is what you are getting at. Is there a graph? This is not to say that one of these small retro-fit kits cant be used, however to be used wisely. It didn't seem too dirty though - I don't think it is the problem, but I could be wrong. Superheat you can consider to be the additional amount of heat. and recharged with mineral oil and 2.2 lbs R12. I had a 1991 BMW switched to 134a by just changing the low pressure charging valve, flushing and refilling with 134 (maybe with 10% . -------------------------"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." You may be just fine on oil - it depends on what compressor you have & how much oil you put in.A T/C is short for Thermocouple. ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. -------------------------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! 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. 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. Here are the basics for converting a system that does not have a charge of R12, its empty. The evap is hard to get at. You either get a system that will function well with R1234yf or get any other type. It is a known suspect that lets heat into the heat exchanger/core even when off because the mono-valve is on the exit side of the heater core. Yes it will work with either Refrigerant! From memory, I put in at least 8 ounces of oil, probably around 10 ounces in there. R134a requires the use of synthetic oil! Hence, let us continue to fix it. Should I do the test again with the the aux fan jumpered? Remember, being aluminum, they lower the temps better, and do not pass off as much heat to the radiator, which then makes it's job easier and lowers underhood temps (besides lowering vent temps inside the car). June 21, 2022 difference between r12 and r134a expansion valve . Whether R134a performs as well as R12 in any given a/c system depends upon system components and the amount of R134a used. If you have 10 ounces of oil in the system, that is contributing to the poor performance as well. In a car ac, using this type of freon 20 years ago was difficult. The aux fan didn't switch on though and I didn't check the high side temperature. The exact amount will vary with each car. It is perhaps possible to locate a unit with a company that purchases close out or distressed merchandise. Hmmmm. It's not just the poor performance - the cooling just stops working after a while. At the moment, the ac is acting up - will work fine for about 15 minutes and then slowly the vent temperatures rise until the compressor switches off. -------------------------"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." Temp switch works the aux fan. I dont know why the cost difference between compressors is so huge, though. All pre-97 XJs use systems with the same basic operating principle, although the parts do change a bit. 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. 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. . In more serious, it could result in cardiac irregularities or death. There is a lot of differences between the R12 and the R134a fittings, you can't mistake them. 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. The difference between R12 and R134a TEV (exp valves) is primarily the 'superheat'. Expansion Valves Catalog E-1, July 2012. Be sure to test @ 1500 to 2000 engine rpm, and record the ambient temp as well. Pray I can let some oil out of the compressor without losing my precious R12. To prevent refrigerant loss you should consider replacing your old hose lines with barrier type hose. 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 . Als nostres webs oferimOne Piece,Doctor Who,Torchwood, El Detectiu ConaniSlam Dunkdoblats en catal. What effect would it have on performance, if any? 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. What effect would it have on performance, if any?At the moment, the ac is acting up - will work fine for about 15 minutes and then slowly the vent temperatures rise until the compressor switches off. -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a, Bohica, You say the drop in performance is not linear with too much oil. It would make a big difference at idle ,in traffic!! Generally, the new amount is 75-85% of the quantity advised by the manufacturer. It slowly gets warmer and warmer in the car, even at highway speeds. 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. Also, R134a cylinders are light-blue in color. Thus, when the system is running, condensing the CO2 is not a problem. But R22 is almost equally damaging. Also, they are mostly used in refrigeration and automotive air conditioning systems. The only difference I can imagine would be the recharge connection. 37 in 2005 tacoma, R134A. Crap! Edited: Sat July 14, 2007 at 10:22 PM by fonebone. Lets take you through the advantages, disadvantages, and differences of these two refrigerants a detailed comparison including R12 vs R134a performance. Rules governing changing from the former to the latter differ between countries. How an A/C Expansion Valve Works. VerticalScope Inc. All Rights Reserved. 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. Hot coolant migrates up through the core by convection (is that the word? You'll get marginally better performance out of the change as the expansion valve is matches the refrigerant characteristics. Inasmuch as R134a has a global warming potential thats over 1000 times more threatening than carbon dioxide, its better than R12. Note that passwords are case-sensitive. R134a has a smaller molecule than R12 so R134a will leak out sooner than R12. R134a vs R12 refrigerant? Bottom line, R134a simply doesn't cool as well as R12. With new R12 no longer being manufactured, the market price soared to $100/pound. I'll put the relay on for that. 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. I'm doing one thing at a time so I know what the cause was. Plus, not releasing the chemical into the air is morally justifiable. Participate in over 40 different forums and search/browse from nearly 3 million posts. It was later found that R-134a had a very high Global Warming Potential, or GWP, number. Skin contact: If the R134a (liquid) comes in contact with your skin, it could cause a burn. 3) A/C Compressor Always On. Comparatively, larger R134a molecules should take more space, and a smaller amount might be required. I'm just trying to help you avoid headaches in the long run. Have a look in the FAQ Section, and look for "Fan clutches & testing them". The ozone depletion potential of a chemical is a factor that shows the level of degradation itll cause to the ozone layer that surrounds and secures the earth from harmful radiation. Took me a while to figure that one out, and how to say that. I have just bought gauges. Carefully study the chart and compare the following: To a large extent, the choice is up to you. If your a/c system is empty/low on refrigerant, if your system has a leak or if you need to open the system, then now is the time to decide which refrigerant you want to use. Before R12 was replaced with R134a in 1995, it was mostly used in trucks and cars. 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. Recharge the compressor with a/c ester oil and a tracer dye. The condensor airflow drops off as the fan clutch dies slowly. 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. Instead, top off R12 with R134a refrigerant. difference between r12 and r134a expansion valve. So if the TXV is OK, and the too much oil situation is not a big problem, then I wonder why the compressor is switching off after about 15 minutes of cooling? Catalog E-1, Thermostatic & Automatic Expansion Valves / Page 1 Table of Contents . R12 is used in several applications like low temperature, medium temperature, and high-temperature applications. The general practice of charging the system with 15% less refrigerant adds to the thermal deficiency of R134a. 5. Until 1995, most cars with air conditioning used R-12 Freon refrigerant which has shown to have an environmental impact. The mechanical fan & clutch should be checked as well. So to keep things simple and to avoid controversy and politics we have R134a. After the initial charge the system is then tweeked : you determine the optimum amount of refrigerant to match your system by monitoring the a/c outlet vent temperature and the high side pressure as you add or remove refrigerant. Expansion valves are an active device, they regulate the flow of refrigerant to the evaporator depending on evaporator temperature. R134a has a smaller molecule than R12 so R134a will leak out sooner than R12. 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. Where would I get some basic info on it, I know nothing about it. We consider the the various types alternative refrigerants that are illegal or not approved to be in two sectors: non-flammables and flammables. There are significant differences between R12, R134a, and R513A, which must be considered when handling, processing, applying, or retrofitting with these refrigerants. Put a relay on the compressor clutch to the aux fan (I like that idea - makes a lot of sense)How does that sound? It won't be optimal, though.On some/many valves, you can adjust them, but that might make matters worse unless you really know what you're doing (which I don't!).RegardsGeorge. I could easily be over at least 2 - 3 ounces over on the oil. If it splashes inside the eye, it could lead to a serious eye problem. Energy usage: R134a is less efficient in cooling compared to R12. The next piece of equipment to track down leaks is a leak sniffer. Once you have replaced the OEM condensor with a PF unit, you will need to make custom hoses to mate with your OEM system. So, instead of using R12, other better options include R401b, R134a, R401a, etc. (On firewall where A/C lines go into cab.) Typically 5 to 6 ounces of a/c oil is adequate but this may vary depending upon the car. What was the ambient when you took that reading?Jumpering the aux fan is a common thing here in the desert. Your average garage that works on a/c on the side probably would not have this. Safe but sorry! But with an R4, better too much than too little.3) A TXV optimized for 134a will be ok with R12.4) The airflow across the condensor is crucial to good performance. Electric fans do wear out. As noted, measure up front as best as you can to get as close to the aftermarket dim. Depending on which circuit diagram fits your car (cough, no vin list exists) you have either one or two switches controlling the aux fan. The analysis focuses on Coefficient of Performance for . we convert older systems where i work all the time and they work fine. 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. Generally you follow the refrigerant flow moving from connection to connection, component to component, and you sniff the a/c vents to check for evaporator leaks as well. A slow loss of cooling at city speeds is usually related to condensor capacity & airflow issues. Swapping the components isnt a herculean task, but recharging the AC is a challenge. This drop can affect energy consumption since the plant will operate for a longer period or a larger plant will have to be installed. R134a is the most widely accepted alternative automotive refrigerant used to replace R12. It can be used applications like walk-in coolers, food and dairy display cases, domestic refrigerators, and beverage dispensers and vending machines. In short, NO! Flushed, vacuumed etc. By using a black light the dye will glow in areas where oil leaks are visible. Inhalation of vapor: Inhaling a large amount of R134a vapor can lead to drowsiness, temporary nervous system depression, and lethargy. A thermostatic expansion valve (TXV) (see Figure 1) is a refrigeration and air conditioning throttling device that controls the amount of refrigerant liquid injected into a system's evaporatorbased on the evaporator outlet temperature and pressurecalled the superheat. The larger fitting goes on the discharge port and the smaller fitting goes on the suction line or compressor inlet / suction port. In no particular order, here's what I've found out regarding answering the questions posed so far:Fonebone - It is definitely an R4 compressor (they left the c off the front and the p off the end, i.e. It is a haloalkane and hydrofluorocarbon (HFC) refrigerant that has thermodynamic properties, potential global warming for one hundred years, and insignificant ozone depletion. These two refrigerants are the older types and are not used in newer refrigeration and air conditioning systems. Can I just use an adapter and save $200? Make sure visiually that no large gaps exist that would allow the air to bypass the condensor on the way to the radiator.B. With the oil leaking out and being told all sorts of things about how these compressors don't have a sump etc, I wanted to be on the safe side. Get to the point where I can walk without crutches2. ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. A/C systems designed to use R-12 will cool best when charged with R-12 refrigerant. Measure what you have now.3) Go back to the page in step one, and find the largest condensor you can put in your vehicle. We've updated our forums!Click here to visit the new forum, Year: 1991Make: Jaguar Model: XJ6Engine Size: 4.0. It is made up of carbon, hydrogen, and fluorine. 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. Discussion in 'Technical' started by Jsarnold, May 25, 2012. Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. They plug all the time. 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. The common problem when converting from R12 to R134a is lack of knowledge or equipment. Is it exponential, squared? Stay home and grill your own steaks and stir your own martini. asia pacific stevie awards 2021. gin, amaretto cocktail. 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. This is the part that controls the system pressures. maintain the A/C of older cars. Its chemical symbol is CH2FCF3. These cheap kits usually have a few cans of R134a (either 12 ounce or 16 ounce), maybe an extra can of refrigerant oil, a few generic R134a charge port adapters and maybe some o-rings.

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