The crossover point is approximately at 64F. ~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446. ). Its chemical symbol is CCl2F2. 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. Hence, let us continue to fix it. Bookmarks: Digg; del . If you have a York, and it is equipped with service valves, you can check & adjust the oil level without discharging the system. Or is there always room for improvement, the more the merrier. Trinary Pressure Switch quantity. Most importantly, the oil used in the plant must always be compatible with the refrigerant used. 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. 5. Instead of using R12, its preferable to use R134a because it is very easy to find in the market, its sold at an affordable price, and is environmentally friendly. SO here's my question. Please enter a valid email address for yourself. and he synthesized R-134a in 1936, 5 years after R-12 was . With the A/c off hi and lo were both at 105psi. The chemical composition of R12 and R134a differ. And yes - expansion valves sometimes need replacing if they are sticky - but a proper AC flush should eliminate the need for a new one if it's already in good condition. 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. The major reason for the replacement of R12 with R134a was to curb future greenhouse effects. 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. Kommentare . How is the vent airflow?I would jumper the aux fan & check the performance. 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. (You must log in or sign up to reply here. The good thing is that after you convert to R134 you can top off the system easily and cheaply. Participate in over 40 different forums and search/browse from nearly 3 million posts. Failure to abide by the EPA regulations can result in expensive fines for either you or your service technician. At the time I thought nothing of it, but now I am thinking maybe that is contributing to the system not working as well as it could. It slowly gets warmer and warmer in the car, even at highway speeds. Recharge the compressor with a/c ester oil and a tracer dye. It can be used applications like walk-in coolers, food and dairy display cases, domestic refrigerators, and beverage dispensers and vending machines. R134a. 4.R404A R134a increased mass transfer resistance to reduce the transmission chamber heat coefficient, while R507 heat transfer coefficient is higher than R404A. But I've read that these car's didn't do too well in the a/c stakes, so that might just be as good as it gets. Thread starter goldNSX; Start date 1 August 2009; Tagged . A slow loss of cooling at city speeds is usually related to condensor capacity & airflow issues. 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. asia pacific stevie awards 2021. gin, amaretto cocktail. Looks like a couple of things happening here1) 80's vintage Eurocars were not "meat lockers". It is usually sold under the brand name, Freon 12. Most vehicles manufactured before 1993 have the R12 A/C system. CONCLUSIONS The differences in the theoretical C.O.P.H calculated for R12 and R134a are consistent with values quoted in the literature. Therefore, its most suitable for both commercial and domestic environments. In practice this means that the car can overheat and the aux fan will stay off! If the water valve is not closing all the way you will have re-heating of the cabin air.The cabin blower was not exactly a powerhouse - it was rated at 200w. Replied by Rich928 on topic R12 or R134a. Then, subtract that result by 0.25 pounds to get the proper amount of R134a charge. 3) A TXV optimized for 134a will be ok with R12. If there is no pusher fan, and you have the room, put one in. Even with proper fan operation, missing seals & air dams can effect condensor effeciency. Yep, definately not a meat locker. The value of carbon dioxide is 1. Also the new quick connect fittings for the high & low side. The difference between the two is about 10,000 btu/h. Discussion in 'Technical' started by Jsarnold, May 25, 2012. 37 in 2005 tacoma, R134A. George Bray on Wed August 31, 2005 5:03 PM I believe the optimum supercool setting will vary slightly between an expansion valve for an R12, as compared to R134a, system. shown for the parallel flow, aluminum condenser that is listed. Reattach the hose lines using new R134a compatible o-rings, lightly lubricate with compressor oil. By using a black light the dye will glow in areas where oil leaks are visible. . 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. I could easily be over at least 2 - 3 ounces over on the oil. I don't believe it is but I had a service guy tell me it needs to be done. Questions About Becoming A Professional Member? The aux fan didn't switch on though and I didn't check the high side temperature. ing the expansion valve, a maximum opening superheat of 7F, and a standard factory air test superheat setting. At 2000rpm, windows open, highest fan, hi pressure stabilized at 225 psi, low 25psi.Ambient 81F, vent 61F. 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. Compared with the cost-performance ratio, R507 is 30-40% . 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. We consider the the various types alternative refrigerants that are illegal or not approved to be in two sectors: non-flammables and flammables. VerticalScope Inc. All Rights Reserved. In a comparison between R12 vs R134a vs R1234yf, R1234yf will pass as the best refrigerant. Next I'll jumper the aux fan. We chose to use 5-6 ounces of oil to be on the safe side: 3-4 ounces for the compressor, 1 oz of oil for the drier and another ounce of oil for system losses. If the system was upgraded by a professional it should have an upgrade sticker. A capacity curve is shown in figure 2 for relative capacity of R134a vs. R12 for evaporating temperatures from 0F to 50F. 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 . Flush with a garden hose - do not use a high pressure washer - you can bend the fins flat & damage the condensor.B. Skin contact: If the R134a (liquid) comes in contact with your skin, it could cause a burn. Its among the greenhouse gases and will keep adding the current problem of heat not leaving the earths atmosphere. Generally this works well for the whole system. 5. Right now you know you have a bit too much, but with a CR4P compressor this is an insurance policy. That way I will have reduced the oil by about 1/3 (assuming the oil is mixed evenly through the system). Also called the orifice tube. Some cars have both an engine coolant temp switch & a refrigerant temp switch, others only the refrigerant switch. If the system was upgraded by a professional it should have an upgrade sticker. absorb by the evaporator to insure all liquid refrigerant entering the evaporator. #19. Use a strong surfactant like Simple Green or Zep Citrus, and soak the fins on the condensor. Automotive Replacement Expansion Valves & Parts; Industrial & Scientific; Customer Reviews. A slow loss of cooling at city speeds is usually related to condensor capacity & airflow issues.You could improve the cooling capacity by replacing the condensor with a high effeciency parallel flow unit. hardly noticable. 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. With that said, I would source the TXV from another source such as NAPA just to avoid any problems. Thanks for the input. Get to the point where I can walk without crutches2. and he synthesized R-134a in 1936, 5 years after R-12 was . There are R134a specific valves that operate at a slightly different pressure, but not for any "old" automotive application that I'm aware of. A/C systems designed to use R-12 will cool best when charged with R-12 refrigerant. You will be fine with a 134a-compatible TXV running R12. Add to cart. I just got some hi/lo side gauges so I'm going to take readings, if they are needed. 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. If ambient is 90 (today) and the output of the condensor is 110, that's pretty good isn't it? A York oil capacity is listed as "6.5 to 9.6 ounces". I've done the FSM test and with 81F ambient, the vent should be 50F. The higher the ambient temperature the higher the high side pressure. However, R134a is better than R12. For instance at 25 F the pressure of R-12 is 24.6 PSI and the pressure of R-134a is 22.1 PSI. So the steps involved are cleaning out the old oil, replacing all the O-rings, replacing the dryer, replacing the expansion valve, and converting the high and low side connectors from Schrader to quick connect valves. Jun 19, 2007. R12 is CFC: Even though R12 is one of the most commonly used refrigerants, it is CFC. Is that why expansion valves are specific to R12 or R134A? difference between r12 and r134a expansion valvewarning signs for a deteriorating patient with covid 19 infection 2022.07.03 18:36 18:36 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. A lower GWP alternative to R-134a had to be found and thus we have the new 1234yf. R134a is the most widely accepted alternative automotive refrigerant used to replace R12. What is usually sniffed are all the connections in the system: hoses and compressor, condenser, drier, expansion valve and evaporator fittings. Don't like the sound of custom parallel condensor. Stability: RR12 doesnt disintegrate even under extreme operating conditions. You can spend long evenings reading about the differences between the two refrigerants. This is the part that controls the system pressures. Also, they are mostly used in refrigeration and automotive air conditioning systems. The larger line at the expansion valve is the suction line. R404a for freezing of product. R12 and R134 are of different chemistry. Very nice! CLUTCH CYCLING SWITCH. However, you can convert R12 to R134a by yourself, save money and keep all the tools purchased. As an example, let's say the R12 charge specification is listed at 2 lbs. 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. The pressure at low temperatures is nearly the same between 12 and 134a. With the knowledge of the differences, youll be able to draw a comparison between R12 vs R134a efficiency. R134a was selected as a replacement refrigerant for R12 because R12 contains chlorine and has a major effect to ozone layer depletion. R12 can move more heat than r134 so when it isn't very hot and the system isn't maxed out you wont be able to tell the difference but when its 110 out and the inside is 140 R12 will cool the cabin temp faster. 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. The typical scenario here is when the car owner buys an inexpensive retro-fit kit from the local auto parts store. 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. Ensure you contact a professional mechanic to do the work for you so you dont end up incurring more costs for yourself. Shorting the plug for the refrigerant switch should run the fan when the compressor is on. R134a refrigerant fittings are different size. #13. It is also used in automotive car conditioning and the plastic industry. From memory, I put in at least 8 ounces of oil, probably around 10 ounces in there. R12 and R22 are both now banned by the EPA in the United States. 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. The only mechanical differences between an R12 system and an R134a system are that R134a systems typically have larger condensers and more powerful compressors. 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. These differences in the valve size can be attributed to the correlation of the cooling capacity with the enthalpy difference and the mass flow, which in . -------------------------"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." 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. The approval is very legal one, governed by the U.S. EPA.
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