divil

The Bentley manual says 8.5oz + 1.7oz is the quantity to use.

I am fitting a new compressor and flushing or replacing everything else. Should the 8.5oz go directly in the compressor, and then the 1.7oz is added to with the refrigerant? I am just wondering because 8.5oz seems like a lot - my new compressor came with about 2oz in it. I know Bentley sometimes makes mistakes. Can anyone confirm if this is right? Thanks

jcman

...Because the oil will find it's place in the system as it is brought back in the low pressure vapor mist, start with 3oz in the compressor and dump 6oz in the accumulator and your gold. Keep in mind that refrigeration oil moves through out the system as a form of a mist state while its liquid state resides mostly in the accumulator along with freon to safely boil-off to not slug punch the compressor.

Prospeeder

yea dont add that much oil lol. I usually add like 4-5oz when replacing a compressor. Now how you gonna flush it. the orifice tube cannot be flushed need replaced, and there are filters built into one of the refrigerant lines that cannot be flushed, and the accumulator cant be flushed and must be replaced. I really dont like the idea of flushing solvents, they can leave residue or puddle up without you knowing and then break down the new oil and destroy the new compressor in no time. Iv yet to have a car return for another compressor from not flushing the system...good luck, a/c can be frustrating and expensive.

divil

Thanks guys...now I'm glad I asked

As regards how I'm going to flush, I am planning to use using Four Seasons Dura II because apparently it evaporates easily. I didn't know there was a filter in the lines that can't be flushed. I was going to try flushing the lines and the evaporator. Everything else is being replaced. I have a whole other thread on it, but the short version is: I had a seized compressor, found a small amount of metal debris on the orifice tube, and now I am putting in a new compressor, condenser, drier and orifice tube.

jcman

Sounds like so far you are on the right track, a little advise from a seasoned 23yr commercial refrigeration tech would be to "triple evacuate" your system to add the most insurance against dreadful containments "like flush solvents” moisture, and non-condensables.

Triple evacuation is a good long vac then a charge of freon or nitrogen enough to purge off then repeat three times, purge and sweep we call it to ensure the crap is out and your dry before you do that holy grail recharge.

I warranty service many systems that require this procedure more so these days with POE basically the same as PAG using 134A, 404A, 410A refrigerants,
so keep in mind as I said before that these oils are very very moisture absorbent to the point that when you open the container its already wet depending on the RH that day.

2.7Lturbo

this man speaks the truth... also you should pull 30in of vacuum, i dont care what anyone else says, on a 2.5 cfm pump 30 is EASY to pull

jcman

I love my 7 cfm dual stage vac pump that can reach 50 microns on a 30psi day with 80% RH, so on a small system he will be gold.

2.7Lturbo

holy ****! i just recommend staying away from anything 1 cfm or less.

divil

OK, well good news so far - it's holding vacuum! I pulled it down for aroud 45 minutes and left it for almost an hour just to see, and it's holding.

Unfortunately I won't get the triple evacuation and refill done tonight by the looks of it. Given that, what is the best state to leave it in overnight? Under vacuum, or with some refrigerant in it? I was thinking I'd leave it vacuuming for a few hours, then leave it empty under vacuum until tomorrow, then do the triple evac & fill - does that sound OK?

jcman

....But I would not leave the system in a vac for too long because the weakest link is the shaft seal that is designed more for positive pressure and any loss is moist air entering right into your new oil, add some freon and vac it again beore you weigh in your final charge.