The difference between R12 and r134a is the BTU carrying capability. Have a look in the FAQ Section, and look for "Fan clutches & testing them". Lets take you through the advantages, disadvantages, and differences of these two refrigerants a detailed comparison including R12 vs R134a performance. It didn't seem too dirty though - I don't think it is the problem, but I could be wrong. Refrigerators generally utilize R22, R32, or 410A-based coolants as their cooling agent. What was the ambient when you took that reading?Jumpering the aux fan is a common thing here in the desert. R134a compressors are substituted as new to retrofit the R12 system compressor part numbers with different height sealing washers. Recomanem consultar les pgines web de Xarxa Catal per veure tota la nostra oferta. The R134a compressor has a 1/8" step in on the high side port. difference between r12 and r134a expansion valve That is a good thing. Most importantly, the oil used in the plant must always be compatible with the refrigerant used. The value of carbon dioxide is 1. You may have heard of a friend that did the job himself with borrowed equipment and 12 or 16 ounce cans of refrigerant. Automotive Replacement Expansion Valves & Parts; Industrial & Scientific; Customer Reviews. Thus, when the system is running, condensing the CO2 is not a problem. Paul -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a. You should keep in mind that recharging your air conditioner improperly could result in more serious damage. With R134a you do not rely on the site glass. It won't be optimal, though. Can I use the one for the R-12? The ARPA Zone/Open Membership Discussion Forums. I dont know why the cost difference between compressors is so huge, though. ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. This refers to BTU's (heat) moved per pound of refrigerant moved. I've got a ball valve I'm going to put in the coolant line before the coolant goes through the firewall to the core. Thanks again. You are indeed 20% out of the OEM spec for cooling. Welcome to rxmechanic.com. I had a 1991 BMW switched to 134a by just changing the low pressure charging valve, flushing and refilling with 134 (maybe with 10% . Formula: (R12 Charge Specification x 0.9) - 0.25 lbs. 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. Only show this user. 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. Until 1995, most cars with air conditioning used R-12 Freon refrigerant which has shown to have an environmental impact. and recharged with mineral oil and 2.2 lbs R12. But as there's not a big difference, people say you can suffice with either. If you find any of these conditions you will want to liquid flush (with dedicated AC flush solution) all the lines, condensers, evaporator (remove the expansion valve) before you proceed further. With new R12 no longer being manufactured, the market price soared to $100/pound. That switch should close @ 52c. 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. ThanksPaul -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a. A/C R12 to R134a Conversion Success | IH8MUD Forum You can use this space to go into a little more detail about your company. 30 deg is pretty coldSystems generally run between 40 and 43 deg. R-134a is widely believed to be the most acceptable R12 substitute. PDF Tecumseh Guidelines for Utilization of R134a It slowly gets warmer and warmer in the car, even at highway speeds. Hot coolant migrates up through the core by convection (is that the word? So you could likely put off buying those new hoses just a bit longer if you wanted. I'm having the same concern. R134a is called tetrafluoroethane (HFC). Statisicaly your friend was lucky. The adjusted tension of this spring is the determining factor in the opening and closing of the expansion valve. A. Pressure/temperature plot of R134a vs. R12 is shown in figure 1. The crossover point is approximately at 64F. If the system was upgraded by a professional it should have an upgrade sticker. I'm curiousSo there is work to do, ie performance should be able to be improved. R-12 to R-134a Conversion. and he synthesized R-134a in 1936, 5 years after R-12 was . Since you will be using less R134a than R12 you do not want to rely on the driers site glass to determine if the system is full. R-401b is the mixture by weight of 61% R22, 11% R-152a and 28% of R-124. If not, you just don't know unless a test is performed. It's helluva humid and hot here in north florida, and I drive around all day for my job. Above this temperature, the saturation pressure of R134a is higher than that of R12; below, it is lower. Hopefully after you have read this entire page you will have enough information to determine which type of refrigerant is best for you. Paul:It is never a waste of my time to chat with someone that understands the problem, and wants to fix it. But as there's not a big difference, people say you can suffice with either. I don't believe it is but I had a service guy tell me it needs to be done. At 40, it is 35psi, which is a difference of 8.9psi. The most common influences which effect the capability of R134a to perform well are the condenser, in some cases the the superheat setting of the expansion valve or the amount of R134a. All fans must work at 100% of the OEM rating. Reattach the hose lines using new R134a compatible o-rings, lightly lubricate with compressor oil. leading to corrosion of expansion valves, capillary tube plugging, and compressor bearing . 5) A/C System Failure. What is a T/C?4. Interestingly, theres one oil type that works perfectly with both types of refrigerants. R134a has an ozone depletion potential of 0, implying that it has a slight effect on the ozone layer. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyers guides, and car and tools comparisons. The OEM spec is 2300 rpm @ 12.6v (engine stopped fully charged battery). PaulJerky King -------------------------1983 Mercedes 240D on R12 and WVO!1192 Mercedes 300D 2.5 R134a1993 Toyota Pickup converted to R134a. 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. Next I'll jumper the aux fan. I had to vaccum the system for 2 hours and recharge 4 oz of PAG oil plus 36 oz of 134A freon (3 cans). June 21, 2022 difference between r12 and r134a expansion valve . On the other hand, R12 has a global warming potential of 10,910. There is more to check.The evaporator must be clean as well as the condensor - was this a smoker's car?You should check the water control valve for the heater core. A discussion of the relationship between valve capacities and superheat set-tings can be found in Bulletin 10-9. Hence, the effect of R12 on global warming is up to 10,000 times higher than carbon dioxide. For example, if your system originally had 36 ounces of R12 then you multiply that by .80 and you have 29 ounce of R134a. In addition, R134a refrigerants are not only used in auto air conditioners, they can be used in freezers, aerosol cans, and refrigerators. It is possible I have 10 ounces (250 ml) in the system. 4.R404A R134a increased mass transfer resistance to reduce the transmission chamber heat coefficient, while R507 heat transfer coefficient is higher than R404A. Low refrigerating effect per pound: In comparison to other refrigerants, the refrigerating effect of R12 per pound is low. 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. Below are the major differences between R134a and R12: The chemical composition of R12 and R134a differ. Bottom line, R134a simply doesn't cool as well as R12. The oil used in R12 systems is not compatible with R134a refrigerant. Anyone know what happens when an R12 expansion valve is used in a system charged with R134A? 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. difference between r12 and r134a expansion valve The compressors used by refrigeration plants to compress gas require oil to help lubricate its moving parts. The whole trick is to sit there in those steam boxes and not perspire, it's vulgar to perspire when driving on public roads.If you want esteem, drive an MB, if you want comfort with 60*F interiors in a 125*F environment, get a Caddy. As per their results . Just had knee surgery yesterday, so I"M not exactly hopping around too well. There are three different refrigerants officially sanctioned by the EPA for automotive usage: r-12, r-. In practice this means that the car can overheat and the aux fan will stay off! 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. Even if the system leaks, repairing the leaks and recharging it with R-12 is usually the best repair alternative. The cure is to use the newer R134a compressors is sealing washers that are different thickness. Super heats are so close, it should not be a major concern.-------------------------The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government. #13. It is made up of carbon, hydrogen, and fluorine. 3 ounces? Mark Baker R-401b is the mixture by weight of 61% R22, 11% R-152a and 28% of R-124. Thomas Jefferson, Thanks,OK, I'm starting to feel a little better about it. Therefore, the R12 refrigerant is illegal, and emitting it is illegal. If you have 10 ounces of oil in the system, that is contributing to the poor performance as well. Additionally, R134a was introduced as a replacement for R22 and R12 in high and medium-temperature refrigeration systems like domestic and commercial chillers. Compressor. Expansion valves are an active device, they regulate the flow of refrigerant to the evaporator depending on evaporator temperature. 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. Most of all the differences gravitate to longevity, functionality, and safety. R404a for freezing of product. I think so. The difference between R12 and R134a TEV (exp valves) is primarily the 'superheat'. You will be fine with a 134a-compatible TXV running R12. . We say generally because the vehicle manufacturer may have a formula already worked out for the R134a conversion process. The problem with these so called drop in replacements is that to properly handle them you may need dedicated equipment to identify the gas and evacuate it for proper disposal. Also, if you want to know what happens if you put R134a in an R12 system, you should first confirm if the R12 system can be replaced or if the refrigerants can be mixed. If 50 degrees across the cond. Air Conditioning Expansion Valve R134a - R12 replacement kit = R134a Charge Level. Not going to mess up your 'do, but you can feel it. We recently created this blog site to enable us to share our knowledge with other automotive mechanics and car owners. Then at least I'd know really where I am on it. I just got some hi/lo side gauges so I'm going to take readings, if they are needed. Once you have replaced the OEM condensor with a PF unit, you will need to make custom hoses to mate with your OEM system. R-134a XV for R-134a use. Consider using the newer valve, even with 134a stamped on the valve. I'm going to check the condensor is way clean too. difference between r12 and r134a expansion valve If there is no pusher fan, and you have the room, put one in. Operating Pressure/Temperature Differences The pressure/temperature curves for R-1234yf and R-134a are very similar. A/C receiver difference between R12 and R134a? | NSX Prime Use strips of foam to couple the two heat exchangers if necessary.B. On this website we are addressing only R134a and not other suggested drop in replacements. Its chemical symbol is CCl2F2. R134a is called tetrafluoroethane (HFC). But R22 is almost equally damaging. 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. It won't be optimal, though. difference between r12 and r134a expansion valve. And I already have so much time and money in this a/c project that I REFUSE to cut any corners as small as a TEV.It doesn't help that most people in the business (at least that I come in contact with, present company excluded, of course!) Is that why expansion valves are specific to R12 or R134A? However, you can convert R12 to R134a by yourself, save money and keep all the tools purchased. However, R12 refrigerants are still used as fire retardants in aircraft and submarines. So I probably put the highest suggested amount in to be safe. We consider the the various types alternative refrigerants that are illegal or not approved to be in two sectors: non-flammables and flammables. 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. Don't like the sound of custom parallel condensor. Though I have seen em run as cold as 12 deg F. If the thermo switch is malfunctioning. Generally this works well for the whole system. From memory, I put in at least 8 ounces of oil, probably around 10 ounces in there. Minor adjustments to the expansion valve and other controls may be necessary for some plans. R12 was once used in many air conditioning units as a refrigerant or cooling agent. Besides, you have a greaseisel. Shorting the plug for the refrigerant switch should run the fan when the compressor is on. The sticker typically has a place to note the amount of refrigerant used, the type of oil and amount of oil, the technicians sign off or name and the date of the conversion. Stopleak is also risky. However, if it is taken close to a fire flame or any electrical heating element, it disintegrates into toxic products. B. 5. 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. If ambient is 90 (today) and the output of the condensor is 110, that's pretty good isn't it? Is that reasonable?Vent airflow is good, I think. I could easily be over at least 2 - 3 ounces over on the oil. 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. 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The R134a compressor has a 1/8" step in on the high side port. Plus, not releasing the chemical into the air is morally justifiable. R-12 is no longer used or produced in many countries and remaining quantities have skyrocketed in price. 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. The good thing is that after you convert to R134 you can top off the system easily and cheaply. Therefore, its most suitable for both commercial and domestic environments. Generally, the new amount is 75-85% of the quantity advised by the manufacturer.