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I have finally completed installation of a new heater core which involves removing the entire ECC including the evaporator, the job was brutal but it's done. It was necessary to drain the R134. No oil came out with the freon. I am now installing a new receiver/dryerand because the system was open for over a week. Upon removing the old dryer I discovered that there was no oil in it. Just a light coating inside it. There was also no oil in the evaporator. It was my plan to replace the same amount of oil that drained out from these 2 parts. Is this normal? Does this mean that the system is low on oil or is it residing somewhere such as in the compressor or condensor. Should I add some oil as a precaution? AC did work fine before I started the project.
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David Hunter
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The oil settles to the lowest part of the system usually. A lot of it resides in the accumulator, and a lot in the condenser and compressor.
I would still add a little bit of oil when you put it together anyway. The evaporator holds little oil because it is usually still sucking liquid through it. It stays pretty "dry" in relation to the condenser or the compressor. Just add a little bit unless you suspect that a significant portion of the a/c oil charge has been depleted through seal leakage or other means.
Add the oil that is specified for the system.
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chris herbst, near chicago
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For an R134a system, it's an "ester" oil, and the generic autoparts places selling "universal" R12 conversion kits (about $20-25) sell this stuff as part of a kit. Unless you're an A/C tech, it isn't legal for you to recharge a system anyway, so it should be done by a shop (and it doesn't have to be a Volvo shop unless it gets into replacing parts.)
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total
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Actually, I'm pretty sure that most (or all) of the factory filled 134a systems are PAG oil, not ester oil. But I didn't want to suggest that in case I was mistaken, since A/C work and parts can be pretty expensive even for a DIY job.
Although the ester oil should mostly work with PAG oil, it is ideal to keep the same oil in the system.
Additionally, the PAG oil is more hygroscopic than is ester oil. Therefore, it acquires more moisture than does ester oil, if the system sits open for too long.
Most factory 134a systems are PAG oil equipped. The 850/70/etc is. I think the 240/940/960 are as well (the ones coming from the factory with 134a).
That, of course, doesn't go for the converted cars. Those would be ester oil systems.
Please correct me if I'm wrong... I could be. A/C is like, my thing though. I like it and I do a lot of A/C work (multiple makes/models) including Volvo. I use a book to reference it, but I want to make sure I've got it right!
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chris herbst, near chicago
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Chris, I am researching a bit on oils and as far as I can tell your comments are correct concerning oils. Here is what i have learned.
Ester oil if for converted systems because it mixes and is compatible with the remnants of the mineral oil.
PAG is used in factory filled R134 systems, there are 2 viscosities depending on the compressor used:
spec ISO150 which is high viscosity for GM and possibly some others
spec ISO 46 which is low viscosity and is used in a long list of compressors including Sanden York Chrysler CCI Nisson Ford and more.
I have not yet been able to find out what our Volvos use but I think it is the low viscosity. When I recharge my S90 I will be adding a small amount of this.
BTW I did discover a small amount of oil hiding in the recesses of the receiver dryer which would not actually drain out but I can see and feel it in there with my baby finger. This is after it sits upside doen for a while. I am going to drill a small hole in the bottom to see how much is there. Perhaps I am being a bit anal with this but that's the way I do things.
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David Hunter
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I don't think there is such a thing as being "too anal" with some parts of cars.
For the benefit of others (you're probably VERY well versed in PAG oils):
The PAG oil is an important fact about later Volvos. It is very hygroscopic, which has often led to evaporator failure and condensers rotting, and all sorts of other things. Plus it eats the system because of the acidity.
This might or might not have anything to do with a lot of the later model evap failures in the Volvo product line, but it has shown to be problematic in other cars. It just shows a very strong need for thorough system vacuuming in the later (R134a) systems, as well as replacing most of the oil when working on the system.
Unfortunately, wiht PAG oil, it has been mentioned frequently that the oil itself will boil off in a vacuum, almost as fast as the moisture in the oil. Therefore some of the oil loses volume when you vac the system and after a couple of recharges like that, you end up with a system that doesn't have enough oil in it.
You can "usually" get away with too much oil rather than too little. You should worry, though, if you are getting twice the oil in the system. That would be way too much. Erring a little bit too much oil, is better than not enough. But a little too much refrigerant is never good with R134a systems.
PS: it would be great if you could post some of the information you get on PAG oil use in the later cars. There isn't enough information out there on later A/C systems. It seems as if a lot of the 800 and S series Volvos are going to the dealer or A/C shops, and it hasn't been covered too well in FWD. I think that Rafael Riverol posted about PAG oil use in the S90 system. I'll try to look it up.
I'm curious because when I talk to people who are well-versed in A/C, it seems as if they really don't know the answers either. Sadly there is so much emphasis on the EPA regulations, that the actual repairs sometimes fall behind.
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chris herbst, near chicago
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Here is a starting place to find more information!
http://www.aircondition.com/
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'96 965 with 16' wheels at 100K. Had '85 745 Turbo Diesel for 200K.
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Look for my infrequent posts there for a few years, mostly in Volvo questions ;)
I don't participate in the board as much as I'd like to. This place takes up a lot of that time. There are some SERIOUS experts on aircondition.com
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chris herbst, near chicago
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I'm positive the factory 134 systems used "PAG" and that is what I used in mine when I rebuilt the system with a new compressor, expansion valve and dryer.
I guessed my compressor overloaded the clutch and broke the links due to low oil, because I found no oil in any part of the system when I took it apart. I think a lot of it leaked by the housing joints and seals in the original compressor as there was a "film" of stuff that was probably decomposed PAG all over the outside of the old compressor.
I added the recomemded oil quantity to the dryer and the compressor when I put it back together.
If I was David Hunter, I'd put a little PAG oil in the new dryer.
If you're really anal about doing it right, you need to remove the compressor and drain the oil so you know exactly how much to replace. (Getting the compressor out is a b$#@h!) I took the alternator off and still had to grind a clearance notch in my wrench handle to get a back bolt loosened.
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'96 965 with 16' wheels at 100K. Had '85 745 Turbo Diesel for 200K.
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Awesome. Thanks.
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chris herbst, near chicago
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Chris and Rob thanks for the response. I will add a small amount of the correct oil when I recharge. I do have the section 609 certificate for AC servicing and plan on charging it myself.
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David Hunter
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That depends on how the refrigerant was removed. If a large leak blew out, it took a lot of oil with it. If it was slowly removed, as in a shop, most of the oil is still in there. Film on various components and a little more in the compressor.
The quantity needed depends on the make of the compressor. I have only a book for 200 series a/c stuff, but it covers several rotary compressor makes. The capacities vary from 300 cm3 to 220cm3. Too large a spread to guess.
Good Luck,
Bob
:>)
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