Automotive Air Conditioning Information Forum

Thanks all, for your replies and advises. Appreciate it.

As it looks now I will follow your advises and not return the compressor.
I will drain and change the oil from PAG 125 to Mineral 525 SAE.

Exactly how much mineral oil should I put in the new compressor, prior to installing it?
Should it be the exact same amount that’s coming out of it, or 10 fl. oz (295 ml) that’s stated on the compressor sticker label?

Or instead, the exact measured oil amount that’s being dried from the OLD compressor?
I am a bit confused here and your opinion will indeed be helpful.

PS! We are replacing receiver drier and expansion valve as well.
Should any amount of oil be put into the new receiver drier?
Thanks

An A6 has a sump that contains most of the oil and typically takes 10-11 ounces, if I recall correctly. So if it came with 10 ounces of PAG in it, I would drain that out, measure whatever comes out, and put back in an equal amount of mineral oil after flushing the compressor a few times with the mineral oil.

It says 10 fl. oz on the new compressor sticker label.
So if I am able to drain 10 oz PAG from the new compressor, I should refill with 10 oz mineral?

On my old compressor, it also says it contains 10 oz. See pictures.
So it doesn’t matter how much oil that’s being drained from the old compressor?

What about the new receiver drier, should I add any amount of oil to it?
Thanks

jllgd wrote: ↑Sat Apr 23, 2022 8:35 pm It says 10 fl. oz on the new compressor sticker label.
So if I am able to drain 10 oz PAG from the new compressor, I should refill with 10 oz mineral?

For all practical purposes, yes. Although a very small amount--maybe 1/4 of an ounce--of mineral oil will remain in the compressor after you flush it, putting in a full 10 ounces--perhap a 1/4-ounce over-fill at that point--won't make a difference.

jllgd wrote: ↑Sat Apr 23, 2022 8:35 pm What about the new receiver drier, should I add any amount of oil to it?

Your option. You could put all the mineral oil into the compressor, which is probably what the factory did when the vehicle was built. Or put 9-1/2 ounces into the compressor and 1/2 ounce into the R/D.

I came upon this nicely written compressor oil balance procedure.
Link here:

https://tccimfg.com/wp-content/uploads/ ... alance.pdf

But it has a different view on how much oil to put in a new compressor.
So main question is, if this procedure is valid for an A6 compressor, that has an oil sump?

Will actually an A6 compressor distribute that much oil into the AC system, from the sump?

In the procedure it says 7 fl. oz of the 10 fl. oz capacity will leave the compressor.
If so, only 3 fl. oz is left in the compressor sump whilst system is running.
Is that enough oil to lubricate and maintain the service life of the compressor?
Thanks

The 10-ounce specification presumes a completely "dry" system. If you didn't flush all the original components or replace them with new parts, then you need to measure the oil that comes out of the old compressor and fill the new compressor with an equal amount, which will likely be less than 10 ounces. If not the former, then some oil will remain in the original components (evaporator, condenser, etc.)