System opened for long time - needs new oil?

[Z2TT]

Hi,

From what I have read PAG oil is hygroscopic and absorbs moisture and can form corrosive acids. My System has not had gas in it since It's opened up to fix some leaks, it has been like this for a few weeks now. Wouldn't moisture have entered and been absorbed into the oil now? and formed acids?

Does that mean I need new oil and cant use the oil thats in there allready? or will the new reciever/drier filter the absorbed moisture from the oil once it's all back together.

Thankyou.

[chemi-cool]

Yes.

Change the oil and leave it under deep vacuum for some time.

[Yuri B.]

Hello.
God only knows how much H2O has absorbed the oil in that system, in case it was not vacuumed or filled for that time with an inert gas, and whether acid has formed in it. You may make the acidity test.

[NoNickName]

But most of all: why the hell didn't you fix it straight away or sealed it?

[cadillackid]

I run into it all thew time.. people remodel their houises.. have a company suck the old gas out and then just move the AC units and leave it t hat way for months...

I always change the oil, put on a new filter / dryer and vac it down for a good long time... it will run as good as new..
-Christopher

[Z2TT]

Somebody seems to disagree that PAG oil will become acidic when mixed with moisture, have a read. The user is test specimen

http://www.acsource.net/acforum/viewtopic.php?f=1&t=7638&p=26364&hilit=viscosity#p26364

He states that the research in the ARTI MCLR program backs up what he says. I'm trying to find information about that program to see if its true or not. He states that in actual fact R12 and Mineral oil when combined with moisture form acids that damage the system, and people assumed the same for R134a/PAG and that it's a misconception.

Thanks.

[D.D.KORANNE]

apart from acid formation , moisture can damage motor windings, hence filter blocs would need change and have a deep vacuum as suggested above . moisture would also be responsible for oil sludge formation ,TEX freez up etc

[Fri3Oil System]

If you really want to be sure that you have eliminated all acids not only from the circuit, you have to use the correct technology, which is today available.

There is a system that enables you to recover and recycle on site any halocarbon refrigerant, and, with this refrigerant, flush/recirculate the plant/installation until you have extrated all oils + acids, til the last drop.
Using N2 will NOT eliminate the acids, since it is not miscible or solluble with them, AT ALL. So if you have changed the compressor, the next one will burn as well.
BY the way, this technology allows you to recycle and reuse the refrigerant afterwards... which a money saving, isn't it

[Tayters]

Somebody seems to disagree that PAG oil will become acidic when mixed with moisture, have a read. The user is test specimen

http://www.acsource.net/acforum/viewtopic.php?f=1&t=7638&p=26364&hilit=viscosity#p26364

He states that the research in the ARTI MCLR program backs up what he says. I'm trying to find information about that program to see if its true or not. He states that in actual fact R12 and Mineral oil when combined with moisture form acids that damage the system, and people assumed the same for R134a/PAG and that it's a misconception.

Thanks.

As I understand it regarding acids, this occurs in POE oils only.
Polyol-Ester oils are made by reacting carboxylic acid with alcohol which results in a mixture of water and ester oil. When dehydrated then only the POE oil remains.
If moisture is allowed to enter the system then this will reverse the process and leave a portion of acid/alcohol mix. Acceptable levels of moisture are 30-75ppm.

PAG (Polyalkylene Glycol) Oil is derived from ethylene or propylene oxide reacted with butyl alcohol. Whilst PAG oils have low pour points (oil flows at low temps) and are compatable with most seals and gaskets they are also hydroscopic but more importantly sport a very low di-electric strength. For this reason they are found mostly an vehicle A/C systems as they use open drive compressors. Another use for PAG oil is vehicle brake fluid out of interest.

This info has been cobbled together from bits and pieces whilst at college back in the day.
Whilst I'm happy with how the different oils react with moisture I am unsure if certain refrigerants also break down and cause nasties to form.