Propane for A/C

NickD

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PAG oil has an unusual characteristic, loves to suck up moisture, and forms an acid that can eat up your AC system from the inside out. Best to draw it deep vacuum, analog is no good need a digital micron gauge to be less than 100 ppm. Then inject it in.

Not like R-12 at all, just pour in the mineral oil, then draw a vacuum before feeding in the refrigerant.

Shaft seal on the compressor can be a problems, can either leak out the refrigerant, or is a gathering point for the mineral or PAG oil and lose that first. If so, compressor will seize, break your single drive belt and if in the middle of no where, you can die. Early York compressors did not mix the oil with the refrigerant, and had a sight glass, one peek and you could see.

Another great accessory is the sight glass, but ambient must be above 80*F, run engine at 1,500 rpm, add refrigerant until bubble free. With this new crap, best to use a digital scale, sure don't make it easy.

Knew guys back then that didn't have a vacuum pump, would just pour in R-12, and release it from the other port to fully charge it. For less than 25 cents a pound was the cheapest way to charge a system.

Been using a single stage vacuum pump for years, with R-134a you need a dual stage.

Back then was only making ten bucks an hour as an engineer, took my car into an AC shop charged 40 bucks an hour, after two hours, hit me with an 80 buck bill, but still didn't get it working. So decided I better learn how to do this. Now some shops are charging 125 bucks per hour and on SS.
 

Mobile Dan

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Solubility...oil in an R-12 system mixes like sugar and water. Oil in a 134-a system does not "dissolve" in the refrigerant, it just gets pushed through the system like an oil slick on a river. I don't know what propane would do...
 

billr

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Hey, nice to hear from you Dan! Are you retired and off traveling now?

Yeah, I have been wondering if there is even any need for the PAG to dissolve. Maybe all I need to be sure of is that it doesn't form some kind of horrible goo when exposed to propane? I think I am going to make a small pressure -chamber with view window so I can see what PAG and liquid propane do to each other. (Nickb2, that link to Bitzer is the only one I have found yet that says PAG and propane are OK; I'm not convinced yet)

I am taking this slow, as I don't want to have the compressor crap out and have to wonder if it is because of the oil/refrig combo or simply because it is 25 years old and been inop for so many years.
 

nickb2

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Here also states pag oil, but which one is better IDK, it indicates 68 grade. But my brain say 46 should suffice for converseion. I dont know where bill is looking on net but I find it everywhere. Lots of ppl looking into this.

table #2 of following. And if you have time, it is 11 pages, I learn something new even at 3-4 am. ;)
 

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nickb2

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In my limited experience, using pag 46 or over to 68 IF U CAN EVEN FIND THAT GRADE IS OK AND WILL NOT TURN TO GOO.

ooops, caps locked. and to lazy to reverse.,
 

nickb2

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page 9 goes further, but the wording of it got the better of me. And I lost focus. Putting low viscous for propane is not knew. I may have said this here before. I dont recommend it for safety reason , but really, those same safety reasons can go fly a kyte as far as I am concerned. A fully charged r1234y gas is probably as flammable as a 1pound squirt of r290. Both use pag oils. MO is way to thin and even up here, we use ac in winter to help defrost. Removing humidity is key up here. Anyway, I hope the other nick likes those charts if he reads them cuz I could make no sense of them, but lest not forget, I quit school once I got my high school thing, then went to pro tech whatever you call it school.

The rest well, call it university of life.

I took time to read, it got interesting then sloped off at page 8 or 9, but dude was interesting and took time to document his findings, and as such, bill r should be ok with pag oil 46 but dont go to 100. ;)
 

NickD

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Think this was Louisville Kentucky back in 1995, several shops were fined around $40,000 for converting R-134a systems back to R12. R-134a evaporators and condensers are far more efficient than R-12, so do get much better cooling, but not nearly as robust as R12 stuff.

Not sure why the EPA is not suing the creators of this planet covered with 75% high heat specific water and a sun that doesn't have a constant temperature output. But blaming things like a tiny can of R12.

Don't get caught putting in propane, the fines are not nearly as bad as shops, but can put a big hole in your savings account. Ha, legal to sell catalytic converter bypass pipes and even advertising them. But don't get caught installing one, and the fines for shops are far greater than DIY guys.
 

billr

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I can not explain why I am not finding good stuff like that Purdue University paper; except that I am just not skilled in searching the web. I have tried all kinds of permutations of "propane", "R290", "PAG", "compatibility", etc.

Back to the Purdue paper. That has a lot of sensible-sounding tech info (most beyond me, too) and is getting me more comfy with the PAG. They used a pressure-chamber like I was thinking of; so saved me that effort! However, note that their Table 3, just before the conclusions, lists three PAG 68 oils tried. PAG1 and PAG3 were "OK" but PAG2 was "NO OK". I didn't see any explanation of the difference in these three PAG 68 oils, or any clue which would be similar to my PAG 100. And, of course, their PAG 100 (PAG5) was "NOT DONE".

Still, I am getting closer to just leaving the PAG 100 in there and am thinking I want to keep the propane charge as low as possible and still get in the mid-30F range at the dash.
 

MrConspark

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check Amazon or your local auto parts store. Fill with solvent and compressed air.
Should never use normal compressed air, Dry nitrogen will clean system better and not allow corrosion causing moisture into system (well besides what's in an open system already)
 

MrConspark

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I can not explain why I am not finding good stuff like that Purdue University paper; except that I am just not skilled in searching the web. I have tried all kinds of permutations of "propane", "R290", "PAG", "compatibility", etc.

Back to the Purdue paper. That has a lot of sensible-sounding tech info (most beyond me, too) and is getting me more comfy with the PAG. They used a pressure-chamber like I was thinking of; so saved me that effort! However, note that their Table 3, just before the conclusions, lists three PAG 68 oils tried. PAG1 and PAG3 were "OK" but PAG2 was "NO OK". I didn't see any explanation of the difference in these three PAG 68 oils, or any clue which would be similar to my PAG 100. And, of course, their PAG 100 (PAG5) was "NOT DONE".

Still, I am getting closer to just leaving the PAG 100 in there and am thinking I want to keep the propane charge as low as possible and still get in the mid-30F range at the dash.
These different oils are all Viscosity differences for different compressor styles like Scroll as opposed to Swash plate piston type. A good conversion oil back in the 90s was Page 68 or 100. But yeah be careful
which oil is used, especially if in a smaller car with a small rotary type compressor and of course if it's new always used the specified oil.
 

billr

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Ooh boy, a new wrinkle! What about the receiver/drier? I see one site that insists only "4A-XH5" desiccant should be used with propane. And another that says the Saturn stock is " -XH9", with no clue of the pore size (4A means 4 angstrom). I can find nothing that explains the -XHx numbers.

I'm about ready to say "screw it" and put propane back in with the existing PAG and receiver as-is; see WTF it does. It has been an inop system, so not much to lose.
 

billr

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OK, I am reading that XH9 or XH7 can be used for propane. I going to accept that, and probably give the propane a real try tomorrow.
 
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