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a/c r134 retro-help


Roadster90
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My a/c lite has been on since January and I was talked into a 35.00 retro kit and was told "anybody can do it". Of course this kit does not provide what is necessary as far as r12 is concerned in the manual:gauges/drawing vacuum-pump motor etc.<BR>Can this really be sucessfully performed without damage to the system/compressor? Anybody versed in the procedure? It doesn't mention replacement of dryer???<P>Thanks,<BR>Nic

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While I don't want to get into a discussion on R134 conversions, if you have had no problem with the A/C before January, I would get a recharge on R12. All systems have small leaks which will eventually cause the A/C light to come on. If a recharege does not keep the system going for at least two years, then I would consider an R134 conversion.

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That's good advice.<P>If your system doesn't leak (much), you can just have it recharged.<P>But if you have a compressor leak, or similar, you'll HAVE to make the switch.<P>This will involve compressor and dryer, at the least.<P>bjh

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If you do a search, there are some really good previous posts on R134A conversions. There are some problems created due to R134A operating at lower system pressures. The lower pressure will cause the A/C warning light to come on. It is suggested in one of these posts to wire a resistor in line with the sensor to overcome this. I am facing the exact same problem. Hope this info helps. smile.gif" border="0

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The R134a refrigerant operates at much higher head pressures than R12. This absorbs more HP from the engine for the same amount of cooling. The actual heat transfer capability will be less after a retrofit. How important this is depends entirely on where you live.<BR> The different temperature/pressure relationships of the two refrigerants defeats the on-board AC self-diagnostics of the BCM.

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All those things are true.<P>Nonetheless, Nic, I've had it done, and I've been pleased with it. Summers in Richmond are hot!.....<p>[ 04-16-2002: Message edited by: BarryJHayes ]

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Guest C.F.Massie

I switched to R134 in my 89 two years ago and have had very little to complain about. The A/C warning did come on now and then but I have figured out how to stop it. Don't set your temp more than 5-10 degrees below the reading for outside temp. The compressor doesn't kick on as often, and I haven';t had a problem since. Also I haven't noticed any drop in the cooling capabilities and I live in Texas and it does get hot down here. The main trick to this conversion is to completely, and I mean completely, purge the system and use the correct lubricant with the R134. Just to be safe I replaced the low pressure switch and she works great

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I'm confused. You said don't set your temperature more than 5-10 degrees cooler than the outside temperature? So if it is 95 degrees outside, you would set your AC temperature no lower than 85. How does this cool your car? I would be melting at 85 in a closed up car. Did I misunderstand something?

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Have had two similar cars retofitted with 134A (Reatta and wife's Bonne) and both will provide more than enough cooling for Central Florida. Key seems to be in having it done by a shop that really understands what they are doing. For example you apparently use less R-134a than R-12 when charging. <P>If the same amount is used, the head pressures will be too high and it will not cool as well (counterintuitive I know but had it demonstrated to me).<P>I do know that mine cools much better now than it did.<P>Do agree that if it just takes a can a year I would not change but my compressor was leaking.<P>Do wonder if the warm idle (625 rpm) is too low to work properly when stopped. Plan to reblow a PROM to set at 725 when I lower the fan turn-on temp.

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Guest C.F.Massie

GSMIKE,<BR>If the outside temp is 95 and you set the set the a/c temp to 85, the most before it is in MAX COOL, your cooler than the outside temp anyway and you acclimate to the difference. In my survival training in the service they always emphasized the human body doesn't need to be cooled much lower than the normal body temp to feel comfortable. Of course that's personal choice, my wife likes her car freezing cold when its hot outside. And she wonders why she is uncomfortable when getting in and out of the car all day. <P>I'm not preaching I just wanted to pass along info on a way to keep the A/C Coolant warning from always popping up when using R-134, if that's what is happening in a persons vehicle.

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OK.. I've done about 10 R-134a conversions and ahve had ZERO problems and NO problems with cooling. The currently available r-134a refrigerant and the oil charge are designed to be compatible with the old r-12 oil. thus you no longer need to retrofit a new compressor and condenser. As far as lower pressures, just pump in a little more r-134. I've even done a 134 conversion on my old 63 buick wildcat and it was just as cold as other similarly aged cars with r-12. I just recharged my trofeo last week and used all 3 cans with the oil charge and according to a professional pressure guage, it's at the correct pressure. Never got an AC system light or msg on the VIC screen after a recharging. <P> The only thing you need to have done is a shop to evecuate the old r-12. you can check to see if you even have anything left in there by pushing in the valve needle on the low side of the system to see if there's any pressure. if there's NO pressure at all, then.. there's no R-12 left in your vehicle. If there's nothing there, then follow your instructions that came with your retrofit kit and you're set.. it's painless and easy as pie. And with testing done with thermometers, there's NO difference in cooling temperature between r-12 and r-134a. There's also a leak detector and leak sealer for r-134a. I would prob not recommend the leak sealer.. prob about as useful and as good for your car as the classic "stop leak" for your radiator. PLEASE don't use that crap in your car.. got a car once that kept overheating no matter what.. yanked the radiator and found the entire bottom of it filled with stop leak. completely plugged up the lower rad hose, gummed up the water pump and left TONS of deposits inside the block. <P>Anyways.. <BR>Good luck on your conversion and FEAR NOT...

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If there is no temp difference between R-12 and R134a, all the manuals ever printed and the chemical manufactures data is all wrong.<P> Also, you should be be suspicious of any recharge proceedure which does not include evacuation of the system with a vacuum pump.

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Every R-134a retrofit kit specofocally states that any remaining R-12 refrigerant is to be evacuated from the system prior to recharging with r-134a by a qualified HVAC service center. Haev yet to see a retrofit kit that did not specificly state this.. if it does not state that, then it is in violation of a federal law which makes it a crime to discharge R-12 refrigerant into the atmosphere. <P> As far as the temp difference, well, like I said.. I've done at least 10 retrofits and ahve seen absolutly NO difference in cooling ability. Countless other people have said the same thing.. So as far as your data is concerned.. Stop being such a stick in the mud. There's nothign wrong with R-134 conversions. Just because you may have had a bad experience or did not read all your instructions, does not mean that the kit is worthless..

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not denying they have different characteristics.. And you are making it extremely hard to not make personal attacks.. Like I said.. There ahs been no difference in TEMPERATURE in the conversions that I have done as well as others that have stated they have seen no difference in the cooling capacity of the R-134a. It doesn't matter if you are some kind of chemical engineer and can tell me every tiny detail between R-12 and R-134a, it still stands that every experience I have had with R-134a has been excellent. Everyone I have known who has switched to R-134a has been very happy. The fact that you can walk into any parts store and even wal-mart abd buy a can of R-134a as oppoosed to having to pay $600 to have a R-12 system recharged is quite a huge convienience even if in your cases the cooling is slightly diminished.. <P> I don't know why you stared taking this discussion so personally, but you shouldn't. To each their own. You can give a little advise and hope for the best, but you aren't trying to make Christians here.. Just relax man..

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The only thing that matters is the heat transfer characteristics and that seems to be similar for the current formulation of R-134a and the original R-12.<P>My experience is that with essentially the same pressures, either will freeze you out.<P>Now when the Bonneville was changed over a few years ago, it did not seem to cool as well and the shop fixed it by removing some of the R-134a. Seems that R-134a is denser than R-12 and if you put the same charge in of R-134a as what the label says for R-12, that is too much.<P>Have seen other places that the proper ratio is 80% as much R-134a as R-12 which would match what I saw. Put the same amount in and it will not cool as well and the pressures will go way high. Sound familiar ?<P>BTW the reason for pulling a high vaccuum is really two fold. First, it removes the moisture from the system through evaporation (why you dod not want to do a/c work when it is real cold). Second, after pulling the vaccuum for a while, you seal the system and watch the pressures for a while. Any leak will show up quickly. <P>Any time I open a system, the dryer is replaced and I pull a vaccuum for a while. Will admit that my "vaccuum device" consists of a vaccuum pump from an Olds diesel belted to a 1/4 hp electric motor. Total investement about ten bucks. Works for me.<p>[ 04-19-2002: Message edited by: padgett ]

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Unregistered professional 134 convertor, how long have you tracked these conversions, what vent temps are accomplished(in degrees), pressures, and long term leak success info can you provide? Not trying to be a smart-ass, just want info for when I run out of r-12.<P> I've not been happy with most 134 conversions so far that I've seen, mostly due to short lived compressors.

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I've had great success in the cars I ahve converted. I don't ahve specific temp data however, I could get temps from the current car I own which has been converted. I used to own a 63 buick wildcat in Texas which I converted over to R-134a. It was verified to be legit R-12 previously. The r-134 kit used is one which was available at Wal-Mart. most all of these kits are SUPPOSED to be compatible with all previous r-12 oil. In the past, the first gen of R-134 was NOT compatible and would break down the r-12 oil and ruin compressors and O-rings, etc.. that's most likely how 134a got it's bad rap. I sold that buick over a year and a half ago to a good friend at Dell Computers who still drives it to this day and says the r-134 still blows nice and cold and has had no trouble.. once every month or so he hooks up the pressure guage to the low side and has never seen a drop in pressure. A 79 trans am I converted via the same kit is still running icey cold to this day needing no additional freon added. I ahve always followed the instructions that come with the kit. 2 cans upside down, one can of oil upside down and top the system off with one full can upright.. has always gotten me to the exact ( give or take 2%) pressure I needed. The Buick took an extra half a can. The other cars i have done have been odd jobbers but have not recieved any complaints as of yet over the last 3 years.

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Guest EDBS0

Wow Nic;<P>Much said on this thread. My 2 cts. <BR>From personal experience I had a compressor seize at 75 on the interstate and yes it was a few hundred miles from home and at night frown.gif" border="0 <BR>Had the car towed to Pep Boys and replaced compressor with a rebuild and converted to R134a. Drove the car an additional 3 summers, some 30K to 40K miles. <P>While I did no impirical measurements the new 134a kept the car as cool as the old freon system. I could not perceive any change in the efficiency or coolness of the system.<P>In the Washington DC area at 95 plus and equally humid the interior would slightly heat up a red light but upon resuming speed the interior quickly cooled off and the fan would run on the lower speeds.<P>For the three years (except for the initial breakdown) I was very happy with the conversion and would highly recommend that you convert.<P>I would expect that if you don't convert this year or next it will be the year after. Like Nike says "<B>Just do it!</B>" If your experience is the same as mine then you will not be disappointed...my voice of experience, Robert

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