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Anyone good at AC or know a good place to look up info? I am converting from R 12 to 134A and as usual do not know what I am doing. I figure if I get the basics right I can always take it to a pro.

JD gave me good info on parts and I have them in hand along with 1000 questions.

There is much info and misinformation on the web, so searching is difficult. I have two questions to start with. 1st would be oil. The compressor for my vehicle comes preloaded with 5 oz of PAG 46 oil. So I have to figure PAG 46 is the right oil. The same compressor is used in a 94 with 134A

But how much for the system?? I am replacing all parts except metal tubing and cooling unit, which will be flushed. The factory service manual states 7oz of mineral oil for 93 V6 with R12 and 7oz PAG46 for a 94 V6 with 134A, they both use the same AC parts so am guessing 7oz is the right amount?

Next would be 134A, there are formulas and tables on the net. But looking at the same info as for the oil. The 93 lists 29oz of R12 and the 94 calls for 26.5 oz of 134A. Then the curve, the 95 calls for 20 oz of 134A!, but the parts for a 95 show different numbers, so leaves me confused?

Dye, what is the right amount of dye to use?

I have acquired a manifold set and vacuum pump, cheap ones but should be good for 1 time use.

93 toyota Sea Breeze V6 auto. Denso 10 PAC15C compressor.

Any and all input greatly appreciated. Jim SW FL

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First of all, you do NOT want to use PAG oil. That is used in systems that were made new for 134A and never had any R12 in them. For a R12 to 134A conversion - you need polyester oil. If your compressor has PAG in it, drain it out. Now, if every AC component in your system was new and had NO old residue - you could use PAG but to do so is near impossible. NAPA sells ester oil as # TWD ME18212

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/A-C-ESTER-OIL-12OZ/_/R-TWEMEI8212_0000999999

Second - oil capacity in a system that has already been used goes by a scale and "guess-work." Your system will already have trapped oil residue in the lines, condensor, evaporator, etc. that you cannot get out. AC charge manuals will give you info on how to make a "best guess" depending on what parts are being replaced, what sort of failure the system had previously, if it was flushed or not, etc.

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One added note. There IS a newer type PAG specially formulated for older systems that have R12 and mineral oil residue in them. It's called "double end-capped" PAG. I've never used it so cannot comment on how well it works. Standard PAG cannot be used in your system.

http://www.amazon.com/Double-end-capped-PAG-oil-viscosity/dp/B00CDDIRA2

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Thanks for the heads up! I have read at least 3 hours on conversions and never seen double ended PAG mentioned. With the info available on the net I am surprised that any 134A conversion works!

So now off on another search, is double ended compatible with PAG46 or does the pre oiled compressor need to be flushed?

Jim SW FL

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Thanks for the heads up! I have read at least 3 hours on conversions and never seen double ended PAG mentioned. With the info available on the net I am surprised that any 134A conversion works!

So now off on another search, is double ended compatible with PAG46 or does the pre oiled compressor need to be flushed?

Jim SW FL

Yes, conventional PAG is not compatible with R12 or any residual mineral oil that will be in your system. Drain the compressor to get the PAG out. The "double-ended" PAG is something new to me. I've just heard about it this year. Back when 134A conversions were very popular, there were complete kits being sold for the changeover. They all came with "ester" oil since it is dual compatible. Seems odd now after 134A conversions are a lot less common - that someone would come up with this new PAG oil - but who the heck knows??

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A web search for double end cap oil brings up a lot of info, that was not there when searching for conversions. The double end cap is still PAG oil and as near as I can tell I will still be using PAG 46. But the delux or higher cost double end cap PAG.

I have seen the video there is some good info there, but he skips a few things. He ended up with too much oil. But he did not mention if the 134A he was using contained oil, some has added oil some does not.

He also mentioned flushing the system, as near as I can tell it is very hard to flush a condenser without professional equipment. Mine was in poor condition so I opted to replace it. Also 134A needs a condenser with more surface area than R12. This was also accomplished by a new parallel flow condenser.

I suspect that poorly performing DIY conversions are due to excess oil unknowingly added with 134A and insufficient condenser. But a disclaimer here, I do not know what I am doing and just trying to stumble through this.

Link that explains the condenser much better than I can. http://www.r3vlimited.com/board/showthread.php?t=246743

In the link you will notice he is using Ultra PAG oil, "Ultra" may mean double capped??

I envy you doing this on a 4 cyl, the V6 is a pain! HTH Jim

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R134 requires PAG oil. Do not worry about the amount of R134 you will need accurate gauges and a temperature chart, charge the high side to match the ambient temperature on the chart it does not act like R12 you can't just dump it in. There is no reason to change the condenser it is only slightly less efficient than R12. But don't worry R134 is on the way out and high presser systems are on the way.

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Now you have me looking. I thought I had a parallel flow condenser, it is instead a serpentine, missed that one. From what I have read a serpentine is 25% more efficient than a tube a fin and a parallel is 33% more efficient. 25 to 33% more efficient seems to be a significant amount if accurate and not manufacturer hype.

The parallel and serpentine are considered non flush-able, another reason to replace as my OE was a serpentine. I am not trying to write a rebuttal to your post, simply looking for the best way to do things.

Why not to flush condenser video. This guy is making you tube videos so obviously an expert. https://www.youtube.com/watch?v=U0O1mcnwjZs What he shows makes sense to me. I believe commercial AC shops now have equipment that can flush newer type condensers, not 100% sure on that? But would guess a new condenser is about the same price as having one cleaned for a DIY'er?

I know someone that did a DIY conversion that I do not know the details of. What I do know is he has replaced 2 compressors in the three years I have known him.

Any and all input always greatly appreciated. Jim SW FL

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What AH says about 134A needing PAG oil is incorrect. That only applies to systems designed for 134A, or older systems with completely clean internal components which is very rare.

Condensors are near impossible to completely clean/flush out if there has been a compressor failure. That's why they either get replaced -or flushed and then aftermarket in-line filters added.

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I should said that AH's statement about PAG is "incorrect" only in my opinion. I doubt there is any rock-solid proof to be found on the subject. I WILL say that good old General Motors issued a service bulletin years back that kind of disputes what most other "authorities" were saying on the subject of R12 to 134A conversions. I for one do not trust everything that once-great company has to say on such things. Maybe I'll cut them more slack if they ever pay back the billions of tax dollars they took from us tax-payers to support their mis-management.

In fact there are two key issues in conversions that were considered "common knowledge" in most if not all AC shops back in the mid-90s and are now often disputed. One is about the need for Ester oil, and Two is about the old "non-barrier" rubber hoses" not being able to properly contain 134A since it's molecular structure was smaller then R12. As to the latter? Makes me wonder why every company that makes AC hoses switched to "barrier hose" since 134A came out. Were they all misled?? I also wonder why "double-ended PAG" was developed if some "experts" say there is no need for it??

Here's the GM bulletin:

From GM TSB #33-12-26: Retrofitting R-12 Vehicles to R-134a - May 10, 1997

"RESIDUAL MINERAL OIL

"THE CONCERN THAT MINERAL OIL IS CHEMICALLY INCOMPATIBLE WITH R-134A AND/OR PAG LUBRICANT HAS BEEN PROVEN TO BE UNTRUE. A NORMAL CHARGE OF MINERAL OIL LEFT IN THE A/C SYSTEM AFTER A RETROFIT TO R-134A WILL NOT DAMAGE THE SYSTEM. MINERAL OIL, HOWEVER, DOES NOT MIX WELL WITH R- 134A, AND WILL NOT PROVIDE ADEQUATE LUBRICATION. TESTS ON BOTH THE ORIFICE TUBE AND TXV SYSTEMS SHOW THAT THE MINERAL OIL PARKS IN PLACES SUCH AS THE ACCUMULATOR, AND DOES NOT APPRECIABLY AFFECT PERFORMANCE OR DAMAGE THE SYSTEM."

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I am thinking of doing a conversion on my 85 sunrader soon, the a/c is kinda weak.

here is a vid on the subject:

https://www.youtube.com/watch?v=B1VG1OHEfAM

I have been lurking on some auto AC forums. After reading about conversions if I had a working R12 system I would fix it and not convert. The phasing out of R12 is causing a glut of it on the market and the price is falling. That and even the Pro's have difficulty agreeing on the right way and products to use. Plus a lot of misinformation.

ie; A well done video is put up by someone flushing a evaporator, no problem. However my condenser has an expansion valve, which many say cannot be flushed and needs to be replaced. The expansion valve is in the evaporator, the evaporator is that thing up under the dash! The guy in the video is flushing an system with an orifice tube and not an expansion valve which is not a problem. Too many grey areas in this.

HTH Jim SW FL

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ie; A well done video is put up by someone flushing a evaporator, no problem. However my condenser has an expansion valve, which many say cannot be flushed and needs to be replaced. HTH Jim SW FL

If an AC system has had a major failure like a trashed compressor - there will be bits of metal and/or teflon stuck in the condensor that is near impossible to get out in entirety. That's why . . after a failure - they are often replaced - or - flushed as best can be done and then an in-line trash filter added.

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I wrestled with the decision to replace the expansion valve. I did not want to take more apart on this. But being a masochist I went ahead with it anyway. I need to buy some golf clubs and give this stuff up!

After struggling to get the cooling unit out I realized I had not unhooked the liquid line :Poster_oops:after that it was easy to remove. During the removal I noticed that it had been removed before, I was not the first in there.

Look what I found in there, no matter what I had done with this it never would have cooled right! I shoulda known!post-8092-0-23275000-1434662905_thumb.jp Left click picture to enlarge.

I knew I was going to have some cooling loss after the conversion, but I think I just compensated for it!!

The foam seals are are also deteriorated badly. Any suggestions on where to get those?? JIm SW FL

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We used R11 to flush systems. GM radial compressors had a nasty tendency to disintegrate we flushed the condensers, lines, evaporators etc. with it, it worked fine. The accumulators and expansion tubes were beyond repair and just got replaced. I’m not sure R11 is sold to the general public any more but it’s still used in the field. jirbus looks like you'll be nice and cool after all this.

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I have been lurking on some auto AC forums. After reading about conversions if I had a working R12 system I would fix it and not convert. The phasing out of R12 is causing a glut of it on the market and the price is falling. That and even the Pro's have difficulty agreeing on the right way and products to use. Plus a lot of misinformation.

ie; A well done video is put up by someone flushing a evaporator, no problem. However my condenser has an expansion valve, which many say cannot be flushed and needs to be replaced. The expansion valve is in the evaporator, the evaporator is that thing up under the dash! The guy in the video is flushing an system with an orifice tube and not an expansion valve which is not a problem. Too many grey areas in this.

HTH Jim SW FL

It is illegal to sell R12 to an unlicensed person yes I know they do but it would run you about a hundred bucks to recharge the system. I used to buy 30# R12 cylinders for $30. R134 by the way is being phased out. But it will take some time so not to worry. The evaporator has the expansion valve it can be removed and then flushed out the condenser is only a matter of removing the fittings. Your expansion valve being inside the air box does not make it too easy to replace did this system work at all before you started? If the valve is toes up you will know right away with your low side pressures in you case it would be a pain and you would have to recharge the system again. Usually the old valves did not give many problems unless some thing blew up in the system it most likely has a screen in the end of the valve just remove the valve and see what it looks like before you give up on it.

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I had an R12 system in unknown condition, but nothing looked very good! I bought a new Denso compressor kit for cheap that included a new expansion valve.

Cleaning this evaporator is a real challenge, starting to wonder if it is worth it? Plus it is a serpentine so difficult for a DIYer to flush.

I was at Costco and they had 30 lb cylinders of 134A for a super price, I do not remember how much, but very cheap. So I have a lifetime supply of 134A!

I seem to have wore out the OPP's emoticon, sorry. Jim SW FL

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All I did was get the different nipples and put the 134A in.

I had a mechanic friend who years ago told me not to bother with all that other crap. I have done 3 vehicles this way - they all work good.

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I wrestled with the decision to replace the expansion valve. I did not want to take more apart on this. But being a masochist I went ahead with it anyway. I need to buy some golf clubs and give this stuff up!

After struggling to get the cooling unit out I realized I had not unhooked the liquid line :Poster_oops:after that it was easy to remove. During the removal I noticed that it had been removed before, I was not the first in there.

Look what I found in there, no matter what I had done with this it never would have cooled right! I shoulda known!attachicon.gifIMG_0150.JPG Left click picture to enlarge.

I knew I was going to have some cooling loss after the conversion, but I think I just compensated for it!!

The foam seals are are also deteriorated badly. Any suggestions on where to get those?? JIm SW FL

First let me say I've been following this topic with both great curiosity and admiration.

There is a saying I've heard where auto AC repair is either really cheap or really expensive. No middle ground what so ever. I had no working cab AC when I purchased mine. Took the belt off so I wouldn't waste the energy to turn the pulley. This topic and your effort really got my curiosity going (doesn't take much). So I decided to do what I always do and look into what is involved. Spurned on by your effort, I searched the web, watched some videos and became ever so slightly more informed. Everyone knows, a little knowledge is a dangerous thing so I'm already self-warned.

I checked the low pressure schrader valve to start with and nothing. Armed with a little knowledge, idle time and money apparently burning a hole in my pocket, I thought maybe replace the o-ring seals, cross my fingers and either pressure test (nothing to lose) or just put enough refrigerant in to see if the compressor will engage. Before it was phased out, I stocked up on R12 but never had reason to use it. Forgot I had it actually. I'm willing to put in a bit of money into this but not sure I want to get to your level of effort (at least not right now)

That all said, this last picture is my why I am hesitant. Spooked really. As a young guy I did car stereo work so am familiar with working at taking dashboards and consoles apart. $64 dollar question, how bad was removing that? The under the hood stuff looks all possible with the 4 cylinder. So an inquiring mind wants to know.

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So I decided to do what I always do and look into what is involved. S

Unless you get lucky and your system is just low but not empty - you will need a vacuum pump before you try to convert or charge your system. That is often a big expense for someone who does not plan on doing a lot of AC work. That is, unless you can borrow one from a friend. You can buy an el-cheap venturi-type vacuum pump if you've got an air-compressor to hook to - for less then $20. But if you live in a high altitude (over 3000 feet) it is almost not worth trying to use. If you cracked open the schrader-valve and nothing came out - you've got a totally discharged system and there must be a reason. Contrary to what some people claim - an AC system in good shape does not leak out - even if 30 years old. My 1979 Datsun system has never been touched since new and I had it parked for 11 years without being run at all. My 1978 Toyota Chinook system still works too but I have no idea how many repairs it has seen in its life. It does still have R12. Same for my 1994 Ford which still has the factory fill. My 1988 Toyota Minicruiser had many slow leaks - so I fixed them and converted to 134A. Works fine so far (two summers now).

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Many humble apologies Don, my intention was to look for info and help. Not send someone else off on a course of self abuse and financial ruin.

I do not know what year RV you have? Mine is a 93 V6 auto. This was one of those projects that went rather quickly My system was dead, old and empty. The first step was unhooking the 2 cooling lines at the firewall. I only did one and attempted to pull the inner wheel well through that tiny little hole. Unhook both.

The first step inside was removing the glovebox with surrounding trim. It is as it looks in the FSM except above the speaker is a clip that comes out with the panel., it is one of those you can not see it you can not feel it, but takes some force pulling straight out to unhook. Don't yank real hard as there are wires attached to the speaker and those need to be unhooked. Once you get the panel out. Maybe a pry bar slipped in there would help??

Then unhook the wires connected to the cooling unit. Then remove the nuts and bolts attaching the cooling unit to the body. Then pull with a little wiggling to get the pipes through the holes, or go out under the hood and finesse them a bit. Unit comes right out.

Total time about 3 hours, not working hard at it, several breaks and double checking on the internet. The biggest time waster was the clip over the speaker, I had no idea what was there and was afraid to damage the plastic. The glove box does not need to be removed separately for this, empty the glove box though.

Page AC-25 93 Toyota service manual. Left click to enlarge.

post-8092-0-23561700-1434749928_thumb.pn

HTH Jim

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I bought a $99 Harbor freight vacuum pump with a 20% off coupon and found a new manifold set on Ebay for $27 with free shipping! In hindsight I would buy better gauges. When I am done with this I will sell them. I do have the luxury of a friend that has a Flea market stand in the winter so will likely break even on them.

Jim SW FL

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I hate to tell you this now but your MH makes a very good vacuum pump the brake booster line will drop the vacuum to about the same as a pump will even just stuck over the gauge center fitting.

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Thanks guys,

These visions of grandeur are no ones fault but mine. Hey, I'm the one who decided this spring that it would be cool to keep rather than dump it off on someone else. Clearly I don't have sense enough to get inside when it rains.

That said, this is my hobby du jour. Some guys have a convertible, bike or hot rod. Maybe a boat that consumes their idle time. This one, while not my choice (wife wanted, found and chose it) I have fully embraced the madness. Got to have something to spend money on needlessly. The fate of the economy and country is depending on it.

Lucky? Yeh, no. I'm not really that kind of lucky. Lucky in marriage, sure. Career, lets not go there but sure, I've done ok. Will this AC unit only need a charge, not likely in the stars for me and I get that. I have only experience with one vehicle where I did anything to the AC. I purchased a Landcruiser in Barstow CA. I however took delivery of it over the Colorado river as it had Arizona plates and doing so meant I didn't have to register it in CA to get it home. Just needed proof of insurance. This however required that I drive with the seller across the desert in very high heat and nope, the factory air was not working. First thing I did arriving in Las Vegas was to stop at the first auto parts store I could find and purchase a charge kit. I dumped two cans of refrigerant in and drove to Denver where it was snowing. Like I said, not terribly bright. That Landcruiser though did hold a charge for several years until my wife suggested (made me) sell it as I needed a van for my company. Still have not forgiven her. Mention how much I miss it every chance I get. What was this thread about anyway?

I don't have any problems buying new tools. Just ask the Mrs. Also a few years back both kids finished college and it was like getting a huge raise. We live pretty conservatively so this cheap motorhome kind of appeals to my senses. If I can fix it up and make it look presentable (or at least less embarrassing when I pull up to the camp grounds) and also make the thing a little more comfortable, hey, why not.

I started looking at the costs. Worst case If I did what jjrbus did and buy all new parts along with a vac pump and and manifold set, it is still within my comfort zone. I found everything but the lines so far. This is still far cheaper than a hot rod, boat or antique car and I can sleep in it if the Mrs tosses me out on my butt.

Mine is an 87 if that makes any difference.

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Mine is an 87 if that makes any difference.

Not knowledgeable enough about these to know?

I spent more money. By appearance the evaporator is a quality unit, but is caked with crud. To clean it I would have to buy a can of coil cleaner and would also need a can of flush fluid and another hour or so labor. This is quickly getting over $20. After flushing it needs to be blown out with clean dry air. I have a wonderful little compressor that does not blow clean dry air. I could buy a filter for the inadequate little compressor, see where this is going? I should not malign my compressor it has served me well for years, but this is beyond its ability's.

I could go to an AC shop and have them flush it, but at what cost??

So I ordered a new Four Seasons for $50, what the hey, I'm going to have a $100,000 Toyota anyway.

The only example I have who expounds on doing it the Wal Mart way. Has bought 2 new compressors in the 3 years I have known him. Plus spent an unknown amount on AC magic elixir. He kinda glosses over that in conversations.

Costs, I was going to buy a Rialta and every one of them has or needs a new transmission, on the Rialta forum the vast majority of posts is about transmissions! Average cost is over $5000. So if I spend less than $5K on this I am ahead.

I hate to tell you this now but your MH makes a very good vacuum pump the brake booster line will drop the vacuum to about the same as a pump will even just stuck over the gauge center fitting.

You did bring it up before and thanks, I need all the input I can get But buying a new tool was more fun, plus I had a coupon. Actually it will not be running when I need to pull the vacuum. I am not going to reassemble everything till I am sure it holds a vacuum. This is a V6 and a pia to work on.

Thanks for the responses Jim SW FL

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Mine is an 87 if that makes any difference.

Not knowledgeable enough about these to know?

Totally understood. I tell people all the time that I am only slightly expert at one 87 Itasca.

Wish I was off camping this weekend rather than hatching up another project but life has once again gotten in the way of leisure.

What I could use from those more knowledgeable with AC in general is where I can find adapters for making up a pressure rig for testing. I have a decent shop set up and a couple kinds of shielding gas for the EconoTig welder. Thinking rather than using air from my compressor, I can use that. Fittings for that I can get at the welding shop. Bridging the two is the big question? I'll plan on ordering a manifold gauge set. Do each of the various fittings have a type name or number that would aid me in my online search for the needed parts to do this? I see the adapters for converting the system but I also have a couple of R12 hoses in the form of can adapters. If I can get it to hold pressure, I'll buy or borrow a vac pump. A seal kit and drier/accumulator is cheap. If the system is totally shot, go to plan jjrbus and shot gun the whole thing.

While I have no experience with AC, I do have a pretty broad background that includes working in vacuum furnace development and powdered metallurgy research some years back. This means I've played with vacuum and gasses and at least have a clue as to safety. In case someone was worried I'd freeze my eye out.

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From reading argon/co2 mix will contaminate the system. The people that do this for a living use nitrogen. Up to you. No idea on the fittings? Jim

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I've got helium but in a pinch, can borrow nitrogen. Or just go with filtered air. More digging to do it seems. My guess is the problem is with the co2 as argon is inert and can't think of why it would be problematic. I have argon not argon/co2 mix. Tig not mig welder. They tried to sell me the mixed gas and had to insist that it wouldn't work properly for my application.

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Nitrogen is cheap for years I used it for AC leak detection and a spray bottle laced with Mr Bubbles even the smallest leak made BIG bubbles!

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A little reading later and the only issue I find with argon is the molecules are larger than nitrogen and it is more expensive. I have argon and a regulator, going to go with that. Now just need to pickup a manifold gauge set plus some R12 to 134a adapters and to find the connector to marry the two systems into a pressure test rig. Can anyone tell me what kind of connector this is? Is it standard 1/4" SAE?

pressure-test-rig.jpg

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I have no idea why it would be problematic? Just parroting what I have read. There is a lot of misinformation on the web.

I use a squirt gun for spraying : ) Jim

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I have no idea why it would be problematic?

Me either. The web is a mixed bag on so many levels. I'm starting to figure it out. Problem is I have R12 connectors, will likely get a gauge set that is 134a and need to adapt to the argon regulator. The connector for the welder going into the regulator is npt. Probably will have to order the gauge set and 134a adapters first then figure out how to adapt it to the regulator. Scoured the Grainger site and Amazon. They have a pump adapter fitting for a 134a charge hose and I could use that other than the reverse side is female flair end. I guess the only solution is a mix of all sorts of connectors.

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I have a set of r12 gauges you can have for postage. Also 10lbs of r12 cheap.

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I have a set of r12 gauges you can have for postage. Also 10lbs of r12 cheap.

I would certainly take you up on the gauges. Don't know if you are looking to keep it as a package deal but I don't need the R12. You can PM me with how much the shipping would be and how to get it to you.

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Ok. Give me a few days. Broke down in ND now. See trip report

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