Mechanic Mixed PAG with POE...

[al4nw31]

Hey, I went to a mechanic that didn't know what they were doing, and they added POE to the PAG system. I wasn't paying attention, and I didn't notice they were adding UV dye with POE until later when I looked closer at pictures of the bottle he used.

So here's the homework I've done so far:

There are two major manufacturers of DEC PAG (Idemitsu and Santech). Why does Idemitsu list their PAG as PVE? When looking up the registered chemical name under the EPA (from the SDS CAS number), it's registered as a glycol, yet they seem to want to call it polyvinyl ester. Very confusing. Makes me worried that it's not compatible with PAG, but clearly that's not true since everyone pours PAG into basically every car out there.

Idemitsu claims that POE's biggest downside is that it hydrolyzes. Paired with the fact that PAG is extremely intolerant of contaminants, should I be worried of the long term effect of mixing the two chemicals? I looked at ester hydrolysis papers that seem to suggest that esters have more issues with maintaining lubricity after exposure to water. With PAG, it seems as though you can simply send the oil through an accumulator/dryer and it will be clean again, so you simply oversize the dryer as a solution to water within the oil. However, it seems as though POE will hydrolyze and is not stable in the presence of water, and that in turn hurts it's longevity in imperfect systems (since eventually it will meet water). This in turn makes me extremely worried about the products of the POE hydrolysis possibly reacting with the PAG (carboxylic acid is one of them).

Denso has a failure analysis paper suggesting that mixing POE and PAG reduces lubricity performance. This paper is what triggered my concern:
https://www.denso-am.eu/products/automo ... -analysis/

And last but not least, my car is a 2015 Accord with an expansion valve, so I cannot flush it using traditional solvents without disassembling the entire dash. Nor is it possible to remove misced refrigerant oil with a traditional refrigerant flush. I read the HECAT flushing guide and there were glimmers of hope in the documents. However, I cannot justify purchasing an H1000, nor will I easily be able to locate one. I could literally replace the entire system quite a few times before it would make sense, and I would probably have to call half the state to find one, as almost all the AC shops I called only had the very basics of equipment. I called six shops asking for a system flush and they all turned me down.

[JohnHere]

What was/were the initial problem(s) you were having with the system in your 2015 Accord that the shop dispensed UV dye and oil into it: Very slow leak over the course of a couple of years, slow leak over a few months, or did the refrigerant leak out suddenly, along with some/all of the oil?

I'm not an A/C lubricants engineer, but I believe the PVE oil you mentioned in your extensive synopsis is used only in residential and commercial systems, not MVAC systems. The only oils I know of that are used in MVAC are mineral oil, POE, PAG, and PAGyf.

Your question, as I understand it, is whether you should flush-out the mixture of PAG and POE oil currently in the system or leave well enough alone. The answer is, it depends.

I religiously avoid mixing refrigerant oils. That being said, if just a trace of POE was put in, I think I would leave it alone. However, it sounds like several ounces might have been added...probably far too much compared to what the system even calls for...along with the dye. If that's the case, I would flush everything out now and start over with a clean system even though that would also mean removing, flushing, and reinstalling the evaporator--a lot of work for sure.

In my mind, I simply wouldn't trust a mixture of perhaps several ounces each of PAG and POE in the same system, which might cause catastrophic compressor failure. In that case, you'll then have to replace at least the compressor, condenser, and receiver/dryer, maybe some or all of the lines/hoses, and flush the rest...a very expensive job, especially if you have it done professionally.

So should you take a chance, skip the flushing now, and run the system as it is? In the words of a famous Hollywood movie actor, "Do you feel lucky?"

[al4nw31]

What was/were the initial problem(s) you were having with the system in your 2015 Accord that the shop dispensed UV dye and oil into it: Very slow leak over the course of a couple of years, slow leak over a few months, or did the refrigerant leak out suddenly, along with some/all of the oil?

I'm not an A/C lubricants engineer, but I believe the PVE oil you mentioned in your extensive synopsis is used only in residential and commercial systems, not MVAC systems. The only oils I know of that are used in MVAC are mineral oil, POE, PAG, and PAGyf.

Your question, as I understand it, is whether you should flush-out the mixture of PAG and POE oil currently in the system or leave well enough alone. The answer is, it depends.

I religiously avoid mixing refrigerant oils. That being said, if just a trace of POE was put in, I think I would leave it alone. However, it sounds like several ounces might have been added...probably far too much compared to what the system even calls for...along with the dye. If that's the case, I would flush everything out now and start over with a clean system even though that would also mean removing, flushing, and reinstalling the evaporator--a lot of work for sure.

In my mind, I simply wouldn't trust a mixture of perhaps several ounces each of PAG and POE in the same system, which might cause catastrophic compressor failure. In that case, you'll then have to replace at least the compressor, condenser, and receiver/dryer, maybe some or all of the lines/hoses, and flush the rest...a very expensive job, especially if you have it done professionally.

So should you take a chance, skip the flushing now, and run the system as it is? In the words of a famous Hollywood movie actor, "Do you feel lucky?"

Yeah, my understanding right now is that the oil + dye requires a fair bit of oil to be added, and since the factory oil fill is 2.37 to 2.77 oz, it’s likely that a large percentage of the system is ester right now.

Right now it looks like it’s just the condenser leaking from the preliminary inspection. In hindsight, I probably should have kept a closer eye on the process, but I had believed the shop was simply adding refrigerant and pure dye.

I suppose I’ll attempt to take the safe route and call more shops. I’m at 6 shops currently that don’t want to deal with flushing the entire system. Any recommendations in Northern California near SF?

And thanks so much, I’m at least more certain now that the listed PAG under Idemitsu’s PVE category is probably still just PAG.

Thanks so, so much for the recommendation!

[tbirdtbird]

I am very experienced, but not at the same paygrade as JohnHere. He is MACS certified. I listen to everything he says. After trying to absorb all this and doing my own research, I would have to vote total flush.
Maybe one of the other hi-paygrade guys will see this post and respond

[JohnHere]

...my understanding right now is that the oil + dye requires a fair bit of oil to be added, and since the factory oil fill is 2.37 to 2.77 oz, it’s likely that a large percentage of the system is ester right now.

According to the specs that I have for your vehicle, the oil amount range is the same as what you mentioned (PAG-46), while the refrigerant amount is 17 ounces net weight of R-134a. I have to wonder why the shop felt compelled to add POE oil to a PAG/R-134a system, though. They could have injected just the UV dye to leak-check it, and the oil problem we're now facing would have been avoided. Actually, you should hold them responsible for making it right.

Right now it looks like it’s just the condenser leaking from the preliminary inspection. In hindsight, I probably should have kept a closer eye on the process, but I had believed the shop was simply adding refrigerant and pure dye.

The condenser is leaking probably because of some type of road debris that was kicked up, damaging it. As a paying customer, I, too, would expect the shop to do a credible job and not mess-up something else.

I suppose I’ll attempt to take the safe route and call more shops. I’m at 6 shops currently that don’t want to deal with flushing the entire system. Any recommendations in Northern California near SF?

One way around flushing the entire system, including the evaporator, is to just replace it with a new one. Doing so will still require getting into the dash, of course, but at least you (or a shop) won't have to worry about having the flushing equipment and solvent on hand to complete the job. The condenser will be replaced anyway, so that will be new and clean as well. If the TXV looks good, I would re-use it.

The compressor should be removed and oil-flushed (no solvent should be used to flush a compressor) a few times to clear out the old oil mixture, then refilled with 2 fluid ounces of PAG-46. The remaining 3/4-ounce of oil can be distributed equally to the condenser, evaporator, and R/D. The lines, unless they have mufflers, will have little to no oil in them and can probably be reused as they are. While you're at it, be sure to replace all the o-rings with new HNBR-type o-rings (the green ones).Then it's a matter of reassembling the system, thoroughly evacuating it, and recharging to specs.

I'm sorry that I don't have any shop recommendations in your area, but someone else reading this thread might know of a good one.

And thanks so much, I’m at least more certain now that the listed PAG under Idemitsu’s PVE category is probably still just PAG. Thanks so, so much for the recommendation!

We're happy to have you on the Forum. Let us know how the repairs turn out.

[maSpain77]

I realize I'm reactivating an old post, but hopefully someone can benefit from me posting this. I've held ASE and Femepa certifications in the past, have worked in automotive A/C shops for about 20 years. While all those big, hard to pronounce therory phrases above are certainly true, POE is non-conducive (used in hybrid/all electric cars, so the oil doesn't conduct high voltage electricity through the a/c system, which could shock anyone working on the car. PAG is conducive, hence used on non-hybrid cars. That said, you will find that some models that come in IC and EV trims, like the 10th gen Civic, will all use POE oil only. I think it's for simplification purposes, to reduce the cost of having to source, produce, and maintain two different products on the shelf, that will ultimately do the same job (mix with the refrigerant and lubricate the compressor). While I'm not expert enough in chemistry to tell you if the oils should be mixed, I can offer this: Mix 1 oz of PAG with 1 oz of POE in a clean, air-tight container, shake it well, let it rest for a week, in a dark, dry cabinet. Past that time, if no separation, color change, or strange reactions have happened... draw your own conclusions.