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Old 21-11-2006, 17:07   #16
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Hi Wheels:

I was able to buy a leak detection kit here in the States that will push a colored gas thru the system and then show where the leaks are.

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Old 21-11-2006, 18:48   #17

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Sorry, PunPun, but "direct replacement" of R12 with R134a is *not* a simple or reliable process unless certain precautions and conversion actions are taken. The lubricant oils are not compatible, the seals are not always compatible, and the "rubber" hoses are not always compatible. After a system has been reseached to find out which of these parts MAY or MUST be replaced, you can look at conversion. Do a conversion by just throwing R134a into an old R12 system...and you may wind up trashing the entire system beyond repair.

"I think we have several issues with why it is so darn expensive" Yeah, so do we. Whoremongering profiteers and ecolunatics among them, mainly. If they'd simply take out the incompetent repairmen and the whores who don't properly reseal systems before filling them, they'd solve most of the problem and R12 could still be $5/lb where it belongs. Given the choice of refilling a car "properly" versus replacing the entire car with a newly manufactured car--which is common in the US--I can't think there's less harm from the manufacture of the whole new car.
I think I'm going to start making up T-shirts that say "Thank the Gods For Global Warming, Our Normal Ice Age Would Be A Real Bitch." (We're supposed to be in a real nasty ice age right now, based on the geological norms for the past coupla million years.)

"But here, we don't have many rfer guys and only one that does cars." Dare I ask, even if he owns you, is he competent?<G> If he's good, just pay the man and don't ask. In the US, you pretty much stand no chance of getting AC fixed properly north of Georgia. In Florida and Texas, they apparently shoot bad AC repairmen, so finding a good one down there is supposed to be simpler. Just look for one without any bullet scars.<G>

"Firstly, we are not allowed to just let the gas go here in NZ. Especialy the old gas. That has to be collected." Same thing in the US.

" If a system comes in with the old gas, it has to be removed and the system "converted" to be able to run on the new stuff." Different in the US, we are still allowed to refill the old systems--but they are supposed to be SEALED not just "topped off" the way many shops used to. And still do with the newer cheaper gasses.

"That costs and seeing as it all tends to be "smoke and mirrors" here, the few that do it charge big time and we as a consumer just presume that is the way it is. " Well, part of the problem with refrigerant gasses is that the gasses, hoses, and lubricants are not compatible and MUST be kept totally segregated. So that means a shop which handles two gasses (R12 and R134a) must have two complete sets of gauges, tanks, reclamation gear...everything. And frankly, if I needed an extra $5000 worth of gear to handle an obsolete gas that only brough in $2500 a year in *gross* business...I think I'd also say "Sorry, we don't do that any more." Too much hassle.

Could be a reason to take a daytrfip to a big city though, eh? Someplace where they have paved sidewalks, electric lights, streetcars, restaurants with real tablecloths and all that stuff too?<VBG>

"I know that there has to be some problem due to age. If I get some wally to try and fault find, the cost would be prohibitive. Then I imagine the seals int eh compressor would most likely be the culprit anyway. So replacing or rebuilding would also be cost prohibitive. "
Well, in the US, a generic remanufactured compressor is about $125-150 and a premium "dealer" OEM branded one, $350-500. Seals can be replaced and replacing the seals and o-rings in a compressor is just plumbing, albeit "plumbing in a surgical clean room" if it is done right.<G>

"I doubt I could even buy the gas from a refrigeration company. It was difficult enough to get one to just fill my boat fridge system. " Here, you need either an EPA license or a business resale license to legally buy it. And then you're looking at either 14oz. cans or 20(?)# bottles, typically $50 for the can and $500-700 for the bottle, which is similar to a propane tank, same size but color coded differently.

"However, I have had a very kind offer from someone on here with supplying some gas and so I may be able to sort this out myself yet. The leak is so slow, that if a top up gets it running efficiently again, I may just require a top up once a year which will last till we replace the car in a year or two." You can buy a leak detector from eBay and other sources, a used one is fine, for $50. A lot of folks are getting rid of the older R12-only equipment cheap. And a lot of that does R12 and R134a just as well as the new models, so it can be used in the future. You're looking at a box with a wand on it, and a "bare" diode at the end of the wand. The trick is, run the car to build up gas pressure, then SHUT the car and run the sniffer wand, very slowly, next to but not touching the AC lines and system. (Not touching because the diode can be fouled.) The trick is to do this in STILL AIR because any breeze will waft away the freon before the sniffer can find it. When a shop tries to do this while your engine is running and the fan is blowing--that's the sign they are incompetent or worse.
Also, you can use a UV light and dye charge. $50 buys a whole kit including the UV lamp, goggles to use with it, AND a set of dyes that can be used in motor oil and other fluids, so you can dye check for leaks in a car or boat engine's oil systems as well. Again, more than one use for it.
And the simplest way to look for leaks, is to run the car (etc) as above, shut it down, and then spray the AC system with soapy water. The escaping gas will make it bubble--but that won't find leaks as tiny as the other two methods will.

The real hard part of leak detection is patience, and access. You usually can't get in to really see things, so sniffing takes patience. And the UV dye tends to blow out all over from the leak, i.e. if the front seal on your compressor is bad, you'll find UV dye sprayed out all over the front of the compressor and the surrounding area, real clearly. (And it sprays back out the fill valve as you are putting it in--so you do that job with rags wrapped around it. Something they don't teach you in the shop manuals.<G>)

All in all, not hard, not beyond what you can do. In the worst case if it is the compressor and you put in a rebuilt one? You also need to replace the "receiver/drier" can ($50) whenever a system is opened. And then pay someone to suck a hard vacuum in the system and refill it--assuming it holds the vacuum.

Or...dress lightly and buy that new car?<G>

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Old 22-11-2006, 00:34   #18
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Wheels a gas called 34m by origin energy that is completely compatable with r12 in fact we use it in milk vats and r12 systems even topping up some systems that still have r12 in them with no adverse affects.Greg
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Old 22-11-2006, 02:01   #19
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“34m” is a performance enhanced R134a gas specifically designed for medium temperature refrigeration and air conditioning applications.
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Old 22-11-2006, 10:26   #20
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The Gas that Chris is sending me is Forane 409A. I did a search on the product this morning and it seems it is a drop in replacement to the R12. It seems it was an interim gas designed back in the very early 90's to replace the banned R12 till a different alternative could be designed.
Of course, the one thing I don't know is, does the AC have R12 or maybe even the 409A. It is a 95 model, so it is possible that it is either as I don't think the alternative gasses were around yet at that time.

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Old 22-11-2006, 11:13   #21

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The "34m" sounds real good, but if you read the last page of the PDF file, it discloses that 34m is not a "gas" rather it is a "gas mix" consisting of:


Tetra fluoro ethane 95%

R600a < 5%
R290 < 5%
Additive < 0.5%

Now, if those all have the same exact vapor pressure, that's fine. But if they do not, and the system has any leakage, they will leak at different rates and then the question is, how well does what's left work?

This is the bane of all mixed-gas refrigerant systems, and the reason why mixed gas systems are *not* generally used. If there is any leakage, you have to empty the system and start over gain, you can't simply stop (or ignore) the leak and top it up.

With a 1995 car, IIRC R12 was already out of commercial use in the US and Japan, I'd say to check because I have no idea what was used in NZ but you might very well have R134a, which makes repairs quick & cheap for you.
"Forane 409A" is also a mixed gas:


LC50: 300,000 PPM (2-HR. – INHALATION-RAT)
40-70 75-45-6 ACGIH TWA = 1000
LC50: 230,000-300,000 PPM (4-HR.-INHALATIONRAT)
10-30 2837-89-0 AIHA WEEL TWA =
1000 PPM
LC50: >200,000 PPM (6 HR INHALATION - RATS)
10-30 75-68-3 AIHA WEEL TWA =
1000 PPM

More vulgarly put, this is a mix of R-22, R-124, and R-142b. R-22 being what we use in central AC systems in the US, even today.

So it will be subject to the same problems. It will be TOTALLY UNSUITABLE FOR USE unless your system is repaired and not leaking at all. If your system is repaired, and does not leak, it might be suitable. It's another DuPont gas and at least in the US, DuPont isn't pushing it as an R12 replacement. (Probably because it is a mixed gas, compatibility aside.)

If you use it, and the system leaks at all...There's no "topping it up", you must purge and refill. That's the bane of all mixed gasses for refrigeration.

If you don't want to leak-test yourself...your local shop, no matter how he works, should be willing to put a dye charge in your system for the price of an hour's labor, including the time it takes them to check the system over for leaks after you bring it back. Typically some days or hours later, so the dye has had a chance to get blown out the leaks.

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Old 22-11-2006, 12:06   #22

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There are also many electronic leak detectors on the market that cost approximately what a refer guy costs. That's why I have a vacuum pump, manifold set and electronic leak detector. It was cheaper to figure out refrigeration myself, buy the equipment and do the whole thing myself.
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Old 22-11-2006, 19:30   #23
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Also remember that all "mixed gas" must be charged as a liquid only, almost all seperate in gas form. And as stated earlier, that if you ahve a leak in a mixed gas system, you will have to do a total evacuation since the differant gases behave differantly at one given operating pressue, which causes the mixed ratio to go out of wack, which could cause larger problems.
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Old 22-11-2006, 20:44   #24
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Hello Alan Wheeler,
I am going off line now - heading to sea for a while.
Please see my last e-mail and respond to my cellphone number about what you want me to do with the gas if you still require it.

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Old 23-11-2006, 14:21   #25
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HVAC (HVACr machanical engineer) when retrofiting from r-12 to r-134a check with the manufacture of the compressor. depending on the make. I sure you will have to change oils for the system. as to using propane!!!!! what temp/pressure chart would you use for propane as refridgerant. oh! by the way propane would eat the motor windings in less than one year if it even lasted that long, plus the heat factor alone could force a premature visit to the pearly gates. I will look into propane research for a refridgerant and charts. I would venture to say at this point, it may even ilegal for marine applacation, what gages would you use and what modifacations to service ports to service a unit? I personaly, as a licensed techie know of no temp/pressure charts for propane base line
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Old 23-11-2006, 16:27   #26

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"when retrofiting from r-12 to r-134a check with the manufacture of the compressor. depending on the make. I sure you will have to change oils"
There's no need to check, different oils are REQUIRED for the two gasses, there is no compatibility for the oils used.

"propane would eat the motor windings in less than one year "
Ah, no, it won't. Cars do not use the same compressors as fixed installations. There is no "motor" in a car's AC system, it is always an "un" sealed, belt driven, compressor with no intrinsic motor. Very different from what's in your refrigerator, sad to say. Which is why refrigerators routinely get 20 years without any gas loss and cars rarely see half of that.

"I would venture to say at this point, it may even ilegal for marine applacation," Illegal varies with governing authorities. On a civilian vessel, not used in commerce, there are AFAIK no regulations that would be relevant here, except the ones that apply in general. (i.e., civilians being barred from buying or installing R12 without a license.) And, this is for a CAR not BOAT application.

"as a licensed techie know of no temp/pressure charts for propane base line" AFAIK there is no license required for the use of PROPANE or AMMONIA as refrigerants in most of the world. At least not here in the US--where the licenses are for the specific refrigerant GASSES used in certain classes of systems. Use a gas that requires no licensing, and you don't require any licensing, unless there's some other local regulation for contrators and so on.

If NZ rules are similar to the US, Wheels can use all the R134a he pleases. Or propane, although I think that's a moot point by now. It's just R12 and a couple of others he might have trouble with, and none of them are likely to be needed in his car.

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