Page 1 of 1

PAG-oiled components in former mineral oil systems. Corrosion Issues?

Posted: Thu Feb 01, 2018 6:41 am
by Wren
Are there any corrosion concerns when using a compressor and condenser from an R-134a (1993 Volvo 240) car in a system that originally came with R-12/mineral oil (1992 Volvo 240)? It seems like I've read that the remnants of the PAG oil that will be present in the compressor and other components will cause problems with the remnants of mineral oil in the old system.

The reason for the swap is that the '93 YM cars came with a parallel-flow condenser that works great with R-134a while the '92 YM cars used R-12 and a tube and fin condenser that doesn't cool nearly as well when they are converted. I want to swap one in from a parts car I found. I would use ester oil in the converted system as I do with all R-134a conversions.

I would simply buy a new condenser for these conversions, but unfortunately, they seem to be NLA.

Re: PAG-oiled components in former mineral oil systems. Corrosion Issues?

Posted: Thu Feb 01, 2018 8:05 am
by Dougflas
Why not just use POE Bava oil?

Re: PAG-oiled components in former mineral oil systems. Corrosion Issues?

Posted: Thu Feb 01, 2018 8:24 am
by Wren
Dougflas wrote:Why not just use POE Bava oil?


How is that different from the ester oil I'm currently using? I bought it from AMA.

Re: PAG-oiled components in former mineral oil systems. Corrosion Issues?

Posted: Thu Feb 01, 2018 9:43 am
by Tim
Oil has improved over the years. The Santech DEC Pags are pretty much as good as you get. BVA still makes a great oil. It's just had to get these days. Santech is claiming you can use thier DEC PAgs with R12 or R134a.

Re: PAG-oiled components in former mineral oil systems. Corrosion Issues?

Posted: Thu Feb 01, 2018 9:09 pm
by Wren
OK great, but that doesn't answer my initial question about using components that were initially used with PAG oil in a system that used to have R-12/mineral oil.

Re: PAG-oiled components in former mineral oil systems. Corrosion Issues?

Posted: Fri Feb 02, 2018 6:33 am
by Cusser
15 years ago I bought a rebuilt compressor that came filled with PAG oil (I tested it). My '88 Mazda truck is R-12.

I drained the oil from the compressor, added 6 oz. R-12-type mineral oil, rotated the compressor about 15 times by hand, drained that out. Then I repeated that. Then I added the correct oz. of R-12-type mineral oil to the compressor, and that lasted 11 years in my truck in Arizona in my daily driver, so I say that was pretty good life.

Condenser and lines can be back flushed out with solvent to remove any PAG oils. If the condenser is non-serpentine and no new ones are available, then you'll have to do the best you can.

Re: PAG-oiled components in former mineral oil systems. Corrosion Issues?

Posted: Sat Feb 03, 2018 9:32 am
by ice-n-tropics
1) Residual R-12 is undesirable in A/C systems which have been retrofitted to R-134a and is evidenced by copper plating on steel parts and degraded oil.
R-12 is miscible/absorbed into mineral oil and is only removed by lengthy deep vacuum or long atmosphere exposure.
2) Ester based oil was a better choice than single end capped PAG in retrofits with residual R-12. Early DEC PAG was problematic but I only have incomplete but positive experience with post 2000 DEC PAG that have claims of improved compatibility.
3) Less than 2 oz. of mineral oil in retrofits is not harmful if 100% of R-12 is removed but there is some internal coating of heat exchangers with mineral oil which is negative for louver temps (approx. 1.5 deg F per ounce of mineral oil ( which basically collects in the cold evaporator). 4 Sezins was including 2 oz. of mineral oil in each reman compressor to reduce infant failures in retrofit and OEM R-134a systems.
hotrodac

Re: PAG-oiled components in former mineral oil systems. Corrosion Issues?

Posted: Sat Feb 03, 2018 9:37 am
by Tim
ice-n-tropics wrote: 4 Sezins was including 2 oz. of mineral oil in each reman compressor to reduce infant failures in retrofit and OEM R-134a systems.
hotrodac


So Ice32 was just a high end mineral oil?