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Car Forum / Honda Cars / July 2005Whats better? R-12 or R134A
I installed my A/C Compressor today and went I bought it the guy told me to buy three cans of the R-12, you can no longer buy the regular R-12, but this stuff is designed so it doesn't damage the Ozone layer as much. It only does about 5% as much damage. Anyways, I bough the three cans, and today went to another shop and the guy installed my A/C Compressor belt, because I couldn't figure how to install the belt. I told the guy that I had R-12 to install into the lines, but he said no because my car had to use the R134, even though I heard you can use the R-12 also. Everyone is using the R-134A the guy at the shop said, where I got my A/C compressor, and the guy said its crap. He said R-12 is designed to stay colder than R-134A, because the R134A has to much oil and just doesn't blow as cold when its very hot. (Daily its in the Mid 90's here, and very humit) The guy at the shop who installed the belt put in R134 into my car, and it blows pretty nice (even though I was ripped off paying $40.00 for half a can). I have seen some cars blow so cold that it seems like your stuck in a room with dry ice, its blowing out ice mist. My whole question now is should I just keep the crappy R134, or is it possible to add R-12? can the two be mixed? or would it screw up my air. Sorry for the long message. I am just excited because I had this 93 Honda Civic for a year and never had A/C until now. I just want to see whats the right thing to do. Thanks >I installed my A/C Compressor today and went I bought it the guy told > me to buy three cans of the R-12, you can no longer buy the regular [quoted text clipped - 29 lines] > > Thanks R134a and R12 are not compatible and can not be mixed. When converting from 12 to 134a all the original oil must be removed, as it does not entrain in 134a and it reacts with the oil for 134a to form acids if any trace of water gets into the system. I have little faith in R12 substitutes. I'm not an expert, but I suspect there's a reason they are not mainstream while R134a is. At least one substitute is isobutane - thermodynamically nearly identical to R12 but very flammable. A collision that punctures the condensor could be spectacular. R12 will only get more scarce, since all the countries that signed the Montreal Protocol have banned its manufacture or importation. Only licensed servicemen are allowed to buy it, and the price (effectively black market) is outrageous. Yes, it does work better than R134a in systems designed for R12, but you don't want to do the full conversion to a true 134a system: compressor, condensor and evaporator.... Da-ching! Short answer - stay with R134a in what you have and get the headaches behind you, instead of in front of you. BTW, the ozone depletion scare for CFCs was laid to rest a full decade after we signed the Montreal Protocol - see http://cloud1.arc.nasa.gov/polaris/polaris.ems.html - but we still have to live with it. Mike Thanks Mike, You been a real help. I am just wondering why my A/C isn't cold enough though. I am pretty sure new cars are all using the R134A correct? My girl-friend drives a 2002 Mazda Millennium, and when her A/C is on it blows so damn cold that you can see a frost being sprayed out. [simlar to when your outside when its freezing outside, and you blow into the air, you see a steam]. If she is using the R134A, and her car is so cold. Why won't mine get cold? it is only cold if I am on the accelerator. If I am sitting at a traffic light waiting for it to turn green. While I am waiting, its just blowing out cool air, but it really isn't cold. My air probably is around 78 degress coming out. Is there anything that can be done to make my air colder? as you know the older cars don't have temperature gauges like the newer cars. With your typical newly designed car you can set the thermostat to a set temperature such as 71 degrees, but with less expensive cars you just push the sliding nob to the blue or red. Thanks > Thanks Mike, > [quoted text clipped - 19 lines] > > Thanks More modern cars have the entire system designed for R134a. As I understand, it involves a different compressor and condensor, and possibly a different evaporator. The compressor and condensor are to accomodate the higher high side pressures R134a requires to pump the same amount of heat as R12 does. Running R134a in an R12 system definitely results in lackluster cooling - my '85 Volvo has that setup; works fine on the freeway, but not in town. Mike >More modern cars have the entire system designed for R134a. As I understand, >it involves a different compressor and condensor, and possibly a different >evaporator. The compressor and condensor are to accomodate the higher high >side pressures R134a requires to pump the same amount of heat as R12 does. >Running R134a in an R12 system definitely results in lackluster cooling - my >'85 Volvo has that setup; works fine on the freeway, but not in town. I'm certainly no expert but I would agree with Mike on this. We had a '93 Lincoln Town Car "converted" to R134a reusing everything but the dryer and it worked exactly as you describe. On the hottest days at idle speed the cooling was hardly what you would call "cool" but get rolling down the road and the performance was good. We had it checked a couple times (different shops) and never found anything wrong. > > Thanks Mike, > > [quoted text clipped - 24 lines] > evaporator. The compressor and condensor are to accomodate the higher high > side pressures R134a requires to pump the same amount of heat as R12 does. Does that mean our vehicle engines must consume more fuel to achieve the higher pressure? > Does that mean our vehicle engines must consume more fuel to achieve the > higher pressure? No. >> > Thanks Mike, >> > [quoted text clipped - 31 lines] > Does that mean our vehicle engines must consume more fuel to achieve the > higher pressure? No - it's a complicated thing (I researched it a lot about 8 years ago) that results in roughly the same amount of energy being required to pump the heat pretty much regardless of the pressure difference. The actual pressures are the result of the pressure/temperature curve for each gas, and the actual compression energy required is more dependent on condensor temperature than on condensor pressure per se. A factor slightly in favor of R134a is the "ratio of specific heats" - essentially a measure of loss as the gas is compressed and expanded. R12 is about 1.13 while R134a is about 1.09 (1.0 is perfect; air is about 1.4). Mike Well, what does it mean a person i using when their car gets to 50 degrees, my girls car gets very, very cold. She must be using R12 right? as I said her car is a 2002 Mazda Millennium. I am wondering because my car is a 1993 Honda Civic, I am sure it is setup to use R12, as the women I bought my car from didn't know anything even about cars, I know she didn't convert anything over. The only problem is the A/C compressor I bought the guy told me to go with R12, as its better when its very hot and humit outside, and even sold me the new style R12, because it has 80% less CFC's comparied to the first style of R12, and the jackass at the shop who installed my belt put in 134A, even though I told him I had the R12, but he told me not to put it in. I think the guy at the shop screwed up my car. It doesn't get cold, and I am pretty sure its for a R12, but honestly, how can you even tell what setup you have? Thanks! Happy 4th of July > Well, what does it mean a person i using when their car gets to 50 > degrees, my girls car gets very, very cold. She must be using R12 [quoted text clipped - 15 lines] > > Thanks! The 02 Mazda gets so cold because the system was designed for R134a, and yours doesn't get as cold because it was designed for R12 and is running R134a as a substitute. Think of it as being like running a different fuel in your engine - diesel will work fine in a diesel engine but will do very poorly in your engine, and vice-versa. I'm sure your '93 was R12 originally, just like my daughter's '93. The current refrigerant details should be spelled out on one of those stickers under the hood, and that should have been changed when the system was converted. Many DIY conversions ignore that important step. Mike thanks mike, you been very helpful |
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