Author |
Message |
syncro surf Samba Member
Joined: June 06, 2017 Posts: 189 Location: Maine
|
Posted: Tue Jul 27, 2021 4:02 pm Post subject: Flushing PAG from new AC compressor to use mineral oil |
|
|
Hi,
I rebuilt my AC system (87 Syncro) last fall with the intent of using red tek and my original compressor. I assembled my new system with mineral oil as that was in my compressor and it's fine with red tec.
I later decided to also replace the compressor, so now I have a compressor filled with PAG.
I can't seem to find any real consensus about how to flush the PAG. Some people say just drain the PAG and fill with mineral, spin the compressor a bit, drain and repeat a couple of times. Others have suggested flushing with ester first as it is compatible with both PAG and mineral.
Anyone done this? I suspect that flushing a few times with mineral before the final fill would probably be fine, but I'd hate to gum up a new system if that is the consequence of doing it wrong.
Thanks. |
|
Back to top |
|
|
djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32584 Location: Reading Pennsylvania
|
|
Back to top |
|
|
syncro surf Samba Member
Joined: June 06, 2017 Posts: 189 Location: Maine
|
Posted: Tue Jul 27, 2021 4:46 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
Thanks - Thats a good call. I just pulled the plug and left it for the night.
I did the initial drain a little earlier and I mixed some PAG with some mineral in a small container. It didn't explode or turn to concrete, so flushing a few times with mineral seems ok. When I put the system together, the smallest quantity of mineral oil I could get was a gallon, so I've got plenty to flush with |
|
Back to top |
|
|
hardway Samba Member
Joined: January 03, 2012 Posts: 416 Location: Fidalgo Island
|
Posted: Tue Jul 27, 2021 5:19 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
I would drain the case through the drain plug first. Then take the refrigerant line plugs off, place them downwards and turn the compressor shaft. There is always more oil but that should get most of it. Discretion is probably the better part of valor here. |
|
Back to top |
|
|
syncro surf Samba Member
Joined: June 06, 2017 Posts: 189 Location: Maine
|
Posted: Tue Jul 27, 2021 5:46 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
Another good call - Thanks! |
|
Back to top |
|
|
skills@eurocarsplus Samba Peckerhead
Joined: January 01, 2007 Posts: 16863 Location: sticksville, ct.
|
Posted: Wed Jul 28, 2021 2:32 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
pag and mineral are NOT compatible AT ALL
it will make jello
i would drain the PAG and use ester as it's compatible
or make dam sure you have all the PAG out of the compressor using a flush agent _________________
gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
Jake Raby wrote: |
Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
Brian wrote: |
Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
|
|
Back to top |
|
|
Zeitgeist 13 Samba Member
Joined: March 05, 2009 Posts: 12115 Location: Port Manteau
|
Posted: Wed Jul 28, 2021 11:15 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
I've used rubbing alcohol and compressed air to flush compressors of residual PAG. _________________ Casey--
'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik? |
|
Back to top |
|
|
syncro surf Samba Member
Joined: June 06, 2017 Posts: 189 Location: Maine
|
Posted: Thu Jul 29, 2021 1:34 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
I went into this fully expecting to find some appropriate flush agent - but all I could come up with is statements like "under no circumstances should you put any kind of solvent into a compressor". I understand blanket statements like that are to protect people from mishaps do to the variables involved. Certainly there is some solvent that can make brief contact with seals and not damage them, but I'm surprised that I can find no discussion.
So far I have drained the PAG, filled and flushed with mineral oil (spinning the compressor) about six times. The mineral oil now drains out nice and clear. I would still flush it with a solvent to be safe.
Zeitgeist - I'm glad to hear about the alcohol. Did you do this on a new compressor? (VAG alcohol?)
Skills - do you know of an appropriate solvent?
Thanks |
|
Back to top |
|
|
djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32584 Location: Reading Pennsylvania
|
|
Back to top |
|
|
bobbyblack Samba Member
Joined: May 21, 2015 Posts: 4348 Location: United States, Iowa
|
Posted: Thu Jul 29, 2021 2:28 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
A while ago there was a thread about cleaning the whole system out (except the dryer) by an old timer here. He recommended going to a truck/travel place and getting a jug of Air Brakes System cleaner. I don't know what it is, but you might search for a thread about it, and look for a post by Terry Kay _________________ '87 Westy 'Flossie','86 Westy 'R1','86 tintop GL - Subi2.2 'J2','83.5 stock tintop L 'ZoomBus','74 Karmann Ghia, '63 Notch |
|
Back to top |
|
|
syncro surf Samba Member
Joined: June 06, 2017 Posts: 189 Location: Maine
|
Posted: Thu Jul 29, 2021 3:01 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
Thanks - I have read TK's threads and did use air brake cleaner to flush my evaporator.
Most flushing discussions are about flushing/cleaning the system excluding the compressor.
I guess what I really need to know is what turns what to goo. When going from mineral to PAG, which is what all the discussions are about, it seems to be accepted that you can have up to 5% residual mineral oil in your PAG and not have a gelling problem. So in that case the flushing method that I used would be ok.
The reverse could be a different story if it is the mineral oil that turns the PAG to goo. If I have any residual PAG there will certainly be much more than 5% ratio of mineral oil present. Does that mean that even a trace amount of PAG will eventually turn to something that will clog my system?
My big mistake was not deciding to replace the compressor in the first place. I could have just coverted to PAG when I assembled everything - but that ship has sailed. |
|
Back to top |
|
|
kourt Samba Member
Joined: August 13, 2013 Posts: 1940 Location: Austin, TX
|
Posted: Thu Jul 29, 2021 3:01 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
The old Terry Kay method, which I have used before, is to use truck air brake antifreeze solution to clean out your AC lines. It does work well for this purpose. I have run it through all components except the compressor.
It works like this: you pour the solution in to a container that can be pressurized. Put the cap on the container and pressurize it with an air compressor. Open your AC system and make sure the solution has a place to go--usually placing an open hose in a bucket. Place the nozzle of the pressurized, loaded container on the open hose and open the nozzle jet. The solution will blast out of the container and through the hose and into your bucket. Use additional compressed air directly in the AC hose to blast out any remaining solution.
There are specialty products from Intermatics that do the same thing. I find that the air brake antifreeze is more available over the counter at my local auto parts store (O'Reilly).
kourt |
|
Back to top |
|
|
Howesight Samba Member
Joined: July 02, 2008 Posts: 3274 Location: Vancouver, B.C.
|
Posted: Thu Jul 29, 2021 3:08 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
Terry Kay recommended air brake antifreeze. I have used it to flush AC lines. It works. Most FLAPS will sell it. The question, as DJKeev has identified above, is whether it will be needed.
There are so many crevices in the compressor where PAG oil could hide that I do think flushing with such a fluid is a good idea to get the PAG out. The air brake anti-freeze typically is mostly methanol. It will remove most of the old oil and if you hit the compressor with compressed air, it will mostly evaporate. The remainder of evaporation (if any) of this liquid will occur when you vacuum the system.
The key thing, if you go this route, is to get the compressed air into the compressor ASAP, repeat the fluid flush again if you choose, compressed air again, and then add your final oil, drain, and add again.
The air brake line antifreeze typically is 60 to 100% methanol. Methanol corrodes aluminum, which is what the pistons and compressor case are made of. This is why you need to blow compressed air through the compressor and then fill with your final oil ASAP if you use air brake antifreeze. Do any such flush outdoors. Wear gloves and a respirator. Methanol is not to be trifled with. If it lights up, you won't see the flame. Keep a garden hose or fire extinguisher close by.
I would never mix these two kinds of oil, PAG and mineral. For what it is worth, PAG is actually a great lubricant and works well with RedTek or R134A. _________________ '86 Syncro Westy SVX |
|
Back to top |
|
|
syncro surf Samba Member
Joined: June 06, 2017 Posts: 189 Location: Maine
|
Posted: Thu Jul 29, 2021 3:23 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
Dave - I'm kind of with you on the just run it, there cannot be much PAG left in there. I'm just trying to dig up as much actual experience as I can before pulling the trigger. I like that Casey has successfully used alcohol. As of now that's my back up plan if I chicken out on the just run it plan. |
|
Back to top |
|
|
syncro surf Samba Member
Joined: June 06, 2017 Posts: 189 Location: Maine
|
Posted: Thu Jul 29, 2021 3:29 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
Is the Methanol ok for the seals and is it just aluminum corrosion that is the concern? |
|
Back to top |
|
|
djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32584 Location: Reading Pennsylvania
|
|
Back to top |
|
|
syncro surf Samba Member
Joined: June 06, 2017 Posts: 189 Location: Maine
|
Posted: Thu Jul 29, 2021 3:59 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
djkeev wrote: |
Don't overthink this. |
Ha - Impossible. |
|
Back to top |
|
|
Zeitgeist 13 Samba Member
Joined: March 05, 2009 Posts: 12115 Location: Port Manteau
|
Posted: Thu Jul 29, 2021 4:14 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
Yes, I flushed the new AC compressor for my TDI Vanagon with rubbing alcohol. I didn't invent this process. It's been used for decades. _________________ Casey--
'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik? |
|
Back to top |
|
|
pdm777 Samba Member
Joined: August 06, 2012 Posts: 348 Location: Clovis, CA
|
Posted: Thu Jul 29, 2021 6:39 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
rubbing alcohol contains water.
Methanol does not.
Methanol is fine to flush lines and compressors.
Make sure you drain ALL of it out,
then run compressed air to evaporate any traces.
Don't overthink it.
A couple hours of methanol exposure will not
dissolve your seals or compromise aluminum.
You'll be surprised how much 'snot' comes out of
the compressor and the lines, old yellow flourescent dye, etc. _________________ 1990 Westy Full Camper |
|
Back to top |
|
|
Zeitgeist 13 Samba Member
Joined: March 05, 2009 Posts: 12115 Location: Port Manteau
|
Posted: Thu Jul 29, 2021 6:47 pm Post subject: Re: Flushing PAG from new AC compressor to use mineral oil |
|
|
Rubbing alcohol also evaporates quite quickly, especially when exposed to compressed air rushing by. Any solvent that lifts the oil and doesn't leave a residue or affect the seals should work. It ain't brain rocketry. _________________ Casey--
'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik? |
|
Back to top |
|
|
|