Given two identical vehicles, each with the same weighted amount of refrigerant, the vehicle with the R134a has the capability to remove more heat (measured in btus) from the vehicle than the same type of vehicle using the same amount of R12. 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 . Instead, top off R12 with R134a refrigerant. . By: james smith underoath; Comments: 0 . Is there more info needed?THanks -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a, Paul:I had to dig a bit deeper - MB made several running changes in the 1983 123'sThere are actually 4 different circuit diagrams for the A/C system that year - just for your 123.123 I found the R4 reference, and it should have 170 Ml of oil in the system.Your aux fan should run at the ambients you listed. I'm not sure. I've straightened the fans I can and sprayed simple green on it, let it soak then hosed it down well. You either get a system that will function well with R1234yf or get any other type. Until 1995, most cars with air conditioning used R-12 Freon refrigerant which has shown to have an environmental impact. It was later found that R-134a had a very high Global Warming Potential, or GWP, number. The problem with using an approved alternative refrigerants other than R134a is that when the system is serviced it requires certain types of fittings, labels and dedicated equipment. R134a and R12 are among the most popular types of refrigerants. Concentration level: The R134a vapor dilutes the oxygen concentration in the air to a low level, thereby causing harm. You'll get marginally better performance out of the change as the expansion valve is matches the refrigerant characteristics. We've updated our forums!Click here to visit the new forum, Year: 1991Make: Jaguar Model: XJ6Engine Size: 4.0. 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. 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. As illustrated in the chart below, the curves below run together nearly throughout the curve, only slightly breaking paths at around 250 psig/150 degrees and above Flammability/Safety R-1234yf has been designated as MILDLY flammable. If the charge is low the compressor will cycle on/off in the max AC position. 5. The evap is hard to get at. . The only mechanical differences between an R12 system and an R134a system are that R134a systems typically have larger condensers and more powerful compressors. 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? R12 was once used in many air conditioning units as a refrigerant or cooling agent. Moreso, it had been banned. From memory, I put in at least 8 ounces of oil, probably around 10 ounces in there. R134a and water have the same abilities to change the state but R134a can do this more rapidly and at a much lower temperature than water. The best oil that runs well with R134a is PAG oil or Polyalkylene Glycol. Can I just use an adapter and save $200? Vent temperatures slowly go down to around 50F with hi speed driving. Even though their common major function is to cool the system, they have many differences. This implies that the discharge pressure of the compressor should be moderate so it can produce the refrigerants condensation in the condenser at the atmospheric temperature. Lasers don't do well on vent temps, a stick thermometer is better in that application. 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 there is a resource I should read first to save you time, let me know. An orifice tube is just a fixed nozzle that pisses refrigerant into the evaporator without any sort of feedback. Its not that difficult but the procedures of evacuation, charging and testing should be done by a licensed a/c technician that is experienced with R134a and your particular car. look at the difference! R12 or R134a - 928 Owners Club Forum Paul -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a. All fans must work at 100% of the OEM rating. Using R134a requires that Polyolester (POE) lubricant must be used in the compressor. What is a good differential? _____ 2012 E350 2006 Callaway SC560 . In a comparison between R12 vs R134a vs R1234yf, R1234yf will pass as the best refrigerant. Talk about what services you provide. difference between r12 and r134a expansion valve. R12 Expansion Valve = 201 830 06 84 R134A Expansion Valve = 201 830 04 84 Is there a difference after all? You can use the R134a retrofit capacity chart for this purpose. Took me a while to figure that one out, and how to say that. With tube & fin condensors in MVAC applications there is never "too much" airflow. 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. How dumb!I will jumper the aux fan and redo the test. A/C R12 to R134a Conversion Success | IH8MUD Forum . I remember I had the wrong seals and it leaked some oil, so I put some more in.Bohica - I tested the pressures. The pressure/temperature curves for R-1234yf and R-134a are very similar. I have one can left, so maybe a plan can be made. in /nfs/c05/h04/mnt/113983/domains/toragrafix.com/html/wp-content . The reason is that the vehicles, for instance, manufactured currently configure the engine for R1234yf refrigerant, making no provision for replacement. Below are the major differences between R134a and R12: The chemical composition of R12 and R134a differ. Trinary Pressure Switch quantity. is good, then I should be looking elsewhere? Rules governing changing from the former to the latter differ between countries. This may be the source of your oil confusion. I could easily be over at least 2 - 3 ounces over on the oil. Putting R12 into a R134 vehicle | AnandTech Forums: Technology SO here's my question. Some 1993 and older R12 systems aren't as 'compatible' as you'd think to switch over. difference between r12 and r134a expansion valve. 4 Stars & Up & Up; 3 Stars & Up & Up; 2 Stars & Up . Do I leave the orignal condensor in, etc?Thanks. The condenser water inlet temperature and flow rate are controlled with the use of a . Before landing on the debate of R134 vs R12 you should know that both R134a and R12 are AC refrigerants types used in refrigeration and air conditioning systems. The car never overheats, if that has any import. You are indeed 20% out of the OEM spec for cooling. 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. 05-25-2017 02:14 AM. The condensor airflow drops off as the fan clutch dies slowly. 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. The cost of recharging the air conditioner is between $150 to $500. The good thing is that after you convert to R134 you can top off the system easily and cheaply. R134a refrigerant is about 10% less efficient in moving heat than R12! Stopleak is also risky. This is the part that controls the system pressures. Hmmmm. The AC usually does not work at all. Lets take you through the advantages, disadvantages, and differences of these two refrigerants a detailed comparison including R12 vs R134a performance. Fitting a PF condensor is not rocket science, but it requires some planning. 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. Since 2010, all home AC systems manufactured use a refrigerant like R134a that has zero ozone depletion potential (ODP). It is mixed with the freon for the most part, and does accumulate in all components in small amounts. Your decision could be made based on economics, environmental concerns, or both. Right now you know you have a bit too much, but with a CR4P compressor this is an insurance policy. About four or five years ago, I guy with an MB came here with the same problem, that tread was over six pages long. The cable is adjustable at the valve arm. R134a is called tetrafluoroethane (HFC). As R134A refrigerant has different operating characteristics and pressures this valve is not necesssry. Warning: "continue" targeting switch is equivalent to "break".Did you mean to use "continue 2"? 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. This kit comes complete with Expansion valve, o-ring kit, and 1ft. The only difference I can imagine would be the recharge connection. (The .133 is the 300D Turbo).So, what does your compressor look like?B. 1.5 ounces - hmmm. The cure is to use the newer R134a compressors is sealing washers that are different thickness. We suggest dumping the old refrigerant oil in a clean container and inspect the oil for sludge or waxing (old oil that has gelled) and contamination (metal particles). The difference between R12 and r134a is the BTU carrying capability. I think so. Thus, when the system is running, condensing the CO2 is not a problem. As for R134a and R1234yf, theres no room for conversion. In 1994 they switched from R-12 to R-134a. hardly noticable. A. Pressure/temperature plot of R134a vs. R12 is shown in figure 1. The typical scenario here is when the car owner buys an inexpensive retro-fit kit from the local auto parts store. An extra half ounce? R134a and R12 are both refrigerants used in vehicle air conditioning systems. Its chemical symbol is CCl2F2. The original expansion valves work very well with R134a. -------------------------"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." The general practice of charging the system with 15% less refrigerant adds to the thermal deficiency of R134a. The name of the oil is Polyol Ester (POE). Accessories Pumps, Cooling Towers, Evap Condensers, etc, Components Valves, Motors, Condensers, Evaporators, etc, Duct Systems Design, Installation & Practice, Piping Systems Design, Installation & Practice, Control System Design, Installation & Practice, Pro's Forum: National Electrical Code (NEC), Pro's Forum: Calculations & Electrical Theory, Pro's Forum: Electrical Business & Marketing. leading to corrosion of expansion valves, capillary tube plugging, and compressor bearing . There are three different refrigerants officially sanctioned by the EPA for automotive usage: r-12, r-. But R22 is almost equally damaging. If you still find it difficult to use R134a in a home AC system, you can check out a comparison of R12 vs R134a fittings to know the refrigerant that best fits the AC system. Any ideas from the info above? Ask Our Pros-Owner Assistance - NO DIY advice will be given. The next piece of equipment to track down leaks is a leak sniffer. Hopefully after you have read this entire page you will have enough information to determine which type of refrigerant is best for you. But R22 is almost equally damaging. of refrigerant insulation tape. . leading to corrosion of expansion valves, capillary tube plugging, and compressor bearing . Recharge the compressor with a/c ester oil and a tracer dye. The primary function of the design engineer is to make things difficult for the fabricator and impossible for the serviceman. I don't want to be chasing ghosts. ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. 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. That is a good thing. The problem with not being an expert is that you don't know what is important and what's not. You can spend long evenings reading about the differences between the two refrigerants. You may need to adjust the valve in a bit to get desired superheat. That way I will have reduced the oil by about 1/3 (assuming the oil is mixed evenly through the system). Figure 2 shows the different phases and pressures the refrigerant . Kommentare . difference between r12 and r134a expansion valve Therefore, the higher the factor of the chemical (compound), the greater its effect on global warming. R404a for freezing of product. Debug the condensor (I am a computer nerd after all!)3. 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. This refers to BTU's (heat) moved per pound of refrigerant moved. And no, you cannot "drain' excess oil out. R134a has the chemical formula CF3CH2F and is known as tetrafluoroethane. There are R134a specific valves that operate at a slightly different pressure, but not for any "old" automotive application that I'm aware of. July 3, 2022July 3, 2022. Automotive Replacement Expansion Valves & Parts; Industrial & Scientific; Customer Reviews. What is the refrigerant property involved that has caused this? We are an automotive mechanic blog that helps mechanics and car users to find the most recent and accurate technical and repair information for their cars. It won't be optimal, though. R134a refrigerant fittings are different size. With the A/c off hi and lo were both at 105psi. Use a drop light in the engine bay, and check the air path from the front of the car at night. 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. The current expansion valve is FF - 1/4 - C. Is it neccesary to replace this valve? Well, I'm not sure it is 'fine' - it doesn't cool very well in 95F weather. It won't be optimal, though. R12 to R134a change expansion valve? - HVAC-Talk: Heating, Air However, R12 refrigerants are still used as fire retardants in aircraft and submarines. I found that in the..Maxposition on the control it will have the compressor running all the time. Flush with a garden hose - do not use a high pressure washer - you can bend the fins flat & damage the condensor.B. ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. We consider the the various types alternative refrigerants that are illegal or not approved to be in two sectors: non-flammables and flammables. A Lot of the fins are bent, especially at the top. Jun 17, 2011. The difference really shows up on the high side. might be due to charge or different compressor and age. Swapping the components isnt a herculean task, but recharging the AC is a challenge. If you are replacing other system components, such as condensers, driers or hoses, you may need to add more a/c refrigerant oil to the system. evarporator, expansion valve plus flushing out the full system and replacing all the o rings. Is it exponential, squared? But as there's not a big difference, people say you can suffice with either. Generally this works well for the whole system. This refers to BTU's (heat) moved per pound of refrigerant moved. I'm also thinking maybe I should go to R134 - it might work better with the right amount of oil and the correct expansion valve. When I compare parts, 93 uses one part number and 94 has a different part number. maintain the A/C of older cars. Above this temperature, the saturation pressure of R134a is higher than that of R12; below, it is lower. But I don't want to waste your time. R12, on the other hand, is called chlorofluorocarbon (CFC). Besides, its technology has been tested and trusted. If not, you just don't know unless a test is performed. CLUTCH CYCLING SWITCH. Break out the new gauges and measure hi and lo at 1500rpm, and do the Merc FSM test to see how we're doing performance wise. The chemical composition of R12 and R134a differ. Superheat you can consider to be the additional amount of heat. But as there's not a big difference, people say you can suffice with either. We recently created this blog site to enable us to share our knowledge with other automotive mechanics and car owners. Please enter a valid email address for yourself. R134a is called tetrafluoroethane (HFC). We say generally because the vehicle manufacturer may have a formula already worked out for the R134a conversion process. 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. When you add fluorescent tracer dye to with the refrigerant oil it helps to track down leaks that push oil out of the system. R134a has an ozone depletion potential of 0, implying that it has a slight effect on the ozone layer. R134a compressors are substituted as new to retrofit the R12 system compressor part numbers with different height sealing washers.
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