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. 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. Besides, you have a greaseisel. July 3, 2022July 3, 2022. 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. The common problem when converting from R12 to R134a is lack of knowledge or equipment. Heres R12 vs. R134a pressure chart. When the ambient air temps get above 80F the gauge readings can run a bit higher on the high side and lower on the low side when using R134a. But R22 is almost equally damaging. You will be fine with a 134a-compatible TXV running R12. J.Harris said: Or if you want to do it like they do in Mexico you can use propane, it's an excellent refrigerant but highly flammable. ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. The #1 question asked by NEW MEMBERS. Blows pretty hard on full. Thanks again. Theres no doubt that R12 refrigerant is one of the first compounds manufactured for the air conditioning and refrigeration world, but it had to be banned. With that said, I would source the TXV from another source such as NAPA just to avoid any problems. Back in that era, my business associates drove those things, brand new, and maybe I should take my Cadillac instead, no they wouldn't be caught dead in a Caddy, people of our esteem should be driving an MB. Plus, not releasing the chemical into the air is morally justifiable. Then, subtract that result by 0.25 pounds to get the proper amount of R134a charge. Poc temps desprs van decidir unir els dos webs sota el nom de Xarxa Catal, el conjunt de pgines que oferirien de franc sries doblades i/o subtitulades en catal. I had a 1991 BMW switched to 134a by just changing the low pressure charging valve, flushing and refilling with 134 (maybe with 10% . We, the Rxmechanic team, have presented a well-detailed comparison of R134a vs. R12. R1234yf is more environmentally friendly and has a global warming potential of 4. The cost of recharging the air conditioner is between $150 to $500. 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. . Before we mentioned that you can add approximately 5-6 ounces of ester oil to the compressor. Even if the system leaks, repairing the leaks and recharging it with R-12 is usually the best repair alternative. By: james smith underoath; Comments: 0 . R-401b is the mixture by weight of 61% R22, 11% R-152a and 28% of R-124. The adjusted tension of this spring is the determining factor in the opening and closing of the expansion valve. If your compressor requires replacement or its seals and o-rings need to be replaced due to leakage, it would be wise at this time to either obtain a compressor that has o-rings and seals that are compatible with R134a or have your unit re-manufactured with compatible components. The problem with not being an expert is that you don't know what is important and what's not. Rxmechanic.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for website owners to earn advertising fees by advertising and linking to Amazon.com. Rules governing changing from the former to the latter differ between countries. I'll put the relay on for that. Your decision could be made based on economics, environmental concerns, or both. BTW, I use a stick thermo in the vents and the laser on the condenser. Though - the valve for a 1991 says R12 on it, and for a 1994, it says R-134a. Reattach the hose lines using new R134a compatible o-rings, lightly lubricate with compressor oil. 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. R134a compressors are substituted as new to retrofit the R12 system compressor part numbers with different height sealing washers. 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. When ever possible you should ask the technician to note the same information on your repair bill and keep a copy in your glove box for future reference. Compared with the cost-performance ratio, R507 is 30-40% . Here are the basics for converting a system that does not have a charge of R12, its empty. But as there's not a big difference, people say you can suffice with either. Carefully study the chart and compare the following: To a large extent, the choice is up to you. R134a refrigerant fittings are different size. I recommend replacing the expansion valve when you do the swap. You do not however need to replace all the o-rings or seals for a simple conversion, it is simply a logical thing to do when and if the time comes to work or replace certain components because of age issues. R134a is the most widely accepted alternative automotive refrigerant used to replace R12. 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. The good thing is that after you convert to R134 you can top off the system easily and cheaply. Whether R134a performs as well as R12 in any given a/c system depends upon system components and the amount of R134a used. This is a great space to write long text about your company and your services. 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. Just because the radiator does not boil people assume that the cooling system is ok. A capacity curve is shown in figure 2 for relative capacity of R134a vs. R12 for evaporating temperatures from 0F to 50F. 10,000BTU conduction heating? This is because R134a. It was later found that R-134a had a very high Global Warming Potential, or GWP, number. All fans must work at 100% of the OEM rating. AFAIK, there is no clutch on the engine fan on the 240D. A discussion of the relationship between valve capacities and superheat set-tings can be found in Bulletin 10-9. Yes, I don't trust the heater valve either. I've straightened the fans I can and sprayed simple green on it, let it soak then hosed it down well. 3) A/C Compressor Always On. R-12 is no longer used or produced in many countries and remaining quantities have skyrocketed in price. I'm going to check the condensor is way clean too. And I lied about the compressor switches on this car - there are 2 switches on the drier - a temp and a pressure switch. 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. and recharged with mineral oil and 2.2 lbs R12. The evap is hard to get at. 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. a 50f delta across the condensor is good, but I suspect that is an idle reading. "Howdy, Folks!" 1.5 ounces - hmmm. Can I just use an adapter and save $200? 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. In large application systems, the vapor density of this refrigerant is usually high. 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. R134a requires a different oil. 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. By after changing just about everything, he got what was termed, satisfactory cooling. However, theyre still used in older plants, systems, and the automotive industry. A/C systems designed to use R-12 will cool best when charged with R-12 refrigerant. R134a is called tetrafluoroethane (HFC). R134a has a smaller molecule than R12 so R134a will leak out sooner than R12. -------------------------"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." 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). Nice to use new gadgets! 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. This would become an expensive investment for a repair or service station to have unique dedicated equipment for every type of alternative refrigerant. For example, if your system originally had 36 ounces of R12 then you multiply that by .80 and you have 29 ounce of R134a. You'll want the expansion valve matched to whatever refrigerant you're using. I mean, really a lot. gital control scheme. B. However, it was found to be a very bad gas for the environment. R134a compressors are substituted as new to retrofit the R12 system compressor part numbers with different height sealing washers. Yes, this was a smokers car. A. Pressure/temperature table for R12, R134a, and R513A is shown in Figure 1. . Before R12 was replaced with R134a in 1995, it was mostly used in trucks and cars. 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. Best for varieties of operating conditions: Its boiling point is -21.6 Celsius. 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. Concentration level: The R134a vapor dilutes the oxygen concentration in the air to a low level, thereby causing harm. If you have 10 ounces of oil in the system, that is contributing to the poor performance as well. This is the part that controls the system pressures. Further production of R12 was banned in some developed countries by the Montreal Protocol because of its harsh effect on the ozone layer. 2) Frost on the Vents. Since the hose is the stock hose, you cannot tell what refrigerant is inside. If not, you just don't know unless a test is performed. 2001-2023 Griffiths Technical Inc. All Rights Reserved. Stay home and grill your own steaks and stir your own martini. Miscibility with oil: R12 can be mixed with the compressor oil no matter the operating condition. With R-12, 30 is 28.4psi and 40 is 36.9psi, for a difference of 8.5psi. R12, on the other hand, is called chlorofluorocarbon (CFC). It may take a couple of tries to get things really clean.The laser is usually close on clean surfaces, but I prefer a T/C. Please enter a password for your user account. Anyone know what happens when an R12 expansion valve is used in a system charged with R134A? hardly noticable. Until 1995, most cars with air conditioning used R-12 Freon refrigerant which has shown to have an environmental impact. Make sure to wear safety gloves, goggles, and shoes when theres a possibility of exposure to the chemical (R134a). compressor, condenser, evaporator and expansion valve are specifically designed for use with R134a. If liquid refrigerant were to exit the evaporator. Nevertheless, if your application is configured only for R12, then you can use it or consider replacing the applications engine.