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Flushing AC Compressor

CSB on Mon October 08, 2007 9:18 AM User is offline

Year: 1991
Make: Chevy
Model: K2500
Engine Size: 5.7
Country of Origin: United States

Could you tell me what the best way is to flush the AC compressor and remove the oil that is presently in the compressor? I have an R4 compressor that I would like to remove the oil from so that I can Mineral oil that is currently in the system to Ester. I know that the compressor is still good since I recently replaced it and the reason for the flush is because I had a leak and I am now converting the system to R134.

Thanks for your help in advance.

2POINTautO on Mon October 08, 2007 9:47 AM User is offlineView users profile

Isnt it just a drain and refill to the proper level, do not assume the amount that came out is the amount to put back in, many times they are low.

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Give all the dirty details
and dont forget the LO & HI pressures
Year, Make & Model would be nice too

CSB on Mon October 08, 2007 11:49 AM User is offline

I understand what you are saying, but what I was interested in was the proper way to flush the compressor. I am flushing the entire system and replacing R12 with R134 so I need to remove all of the mineral oil that is in the system, which means that I will be needing the 8 ounces of ester oil to replace the mineral oil. Before I can do this, I need to remove the oil from the compressor.

I should have looked further into this forum, because they have the information that I need in the Automotive Air Conditioning Procedures, Tips and FAQ section.

http://www.autoacforum.com/messageview.cfm?catid=20&threadid=12050&FTVAR_MSGDBTABLE=

I have not recharged the system yet, therefore I do not know the high and low pressures. I will get that once I have flushed and recharged the system.

Thanks for the input.

TRB on Mon October 08, 2007 11:55 AM User is offlineView users profile

Drain the oil and then add some of the type of oil you intend to use. Turn the hub of the compressor 10 times or so and drain that oil. Then add back the required amount needed for your project.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

iceman2555 on Mon October 08, 2007 2:32 PM User is offlineView users profile

It seems as if this DIY'er is following the retro fit procedure to the 'nth letter'.
It should be noted that the compressor does not need to be flushed...or completely clean of mineral oil. Since POE's are being utilized....they will mix with the new POE. The extra oz or two of mineral that remains will not result in a burden of excessive lubrication in this system. Removal of lubricant, draining, or flushing as TRB suggested should be more that sufficient for this repair procedure. From past field testing...the residual mineral lube may in fact be of benefit at initial compressor engagement...esp if the system is being recharged a can at the time. The residual coating of mineral lube may offer additional lubricant benefits until the system is fully charged and the migration of lubricant begins.
What ever procedure is followed...insure that there is sufficient lubricant in the accumulator to supply the compressor during the recharge procedure....add Lapp 5-6 oz to the accumulator inlet.....the remainder into the compressor.
Recharge until the inlet and outlet of the evap are the same temp....insure that the engine cooling system is up to par....esp the fan clutch. If over three years of age..or 50k miles...replace the darn thing.
Good luck !!!!!

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

TRB on Mon October 08, 2007 2:42 PM User is offlineView users profile

Ice not to but heads with you again. But you are assuming the replacement compressor is going to come with mineral oil. I highly doubt many remanufactured compressors are being shipped with mineral oil these days. Please feel free to correct me if I wrong on that. I'm more concerned about getting the shipping oil out of a compressor. I also think it helps remove some of the manufacturing debris. Ever seen that nice gray "fresh" oil that comes out of a remanufactured compressor.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

2POINTautO on Mon October 08, 2007 3:00 PM User is offlineView users profile

On a convertion, the old oil is concidered necessary (a little that is) to help keep the rubber hoses coated on the inside, to help seal them, since you are not upgrading to a newer barrier hose like a true retrofit would call for.

I would not want to flush a compressor DRY and then turn it by hand with the new oil just installed, I have seen how easy it is to scratch these things with even your finger nail, drain over night if you will but IMHO, do not chemical flush it.

-------------------------
Give all the dirty details
and dont forget the LO & HI pressures
Year, Make & Model would be nice too

TRB on Mon October 08, 2007 3:50 PM User is offlineView users profile

Now I have heard many say the mineral oil coats the inside of a hose. Does anyone really have proof that this is the case? I don't think I have ever heard a hose manufacturer claim this. Sure they want to sell hose!! So maybe they do not want to let the cat out of the bag. But I would like to see some data backing up this claim. Many years ago I watched what R134a did to "new" non barrier hose. After seeing that I just would not run R134a in non barrier hose period.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

2POINTautO on Mon October 08, 2007 3:58 PM User is offlineView users profile

It kind of fits in the automotive world of myths, like if you clean your intake manifold with really good carb cleaner, then you get this funny looking surface, not knowing that it was a type of epoxy barrier, then all of a sudden you start to have lean running problems because the aluminum intake just became pourous and its leaking air, now who ever heard of that before.

-------------------------
Give all the dirty details
and dont forget the LO & HI pressures
Year, Make & Model would be nice too

iceman2555 on Mon October 08, 2007 8:20 PM User is offlineView users profile

From the original post...seems he has already changed the compressor and is merely seeking to change the type of refrigerant....of course, I could have read that incorrectly.
If this is the case...and the compressor is still operational....I see no need to remove the mineral lubricants. Just my $.02 worth.
As far as the hose question....seems that when the natural rubber lined A/C hoses were exposed to mineral lubricants for a extended period of time....the lubricant tends to permeate into the hose liner. Can think of many instances...back in the day...when we would remove a hose fitting for replacement and the inner hose liner would be as hard as plastic...actually almost to the point of being brittle. I think this is the condition that is being discussed. In this condition, the inner liner acts as a 'barrier' for the new refrigerant (134a).
Never have seen any test on this factor...just remember all the hoses that had to be replaced because of this condition....when trying to insert the new fitting the hoses would actually break apart inside. So it is understandable that this 'hardened' condition could prevent the seepage of 134a.
Now this factor is for all hoses...except those used on Chrysler products....heck..those things leaked about every 1/2 in.
Agreed on the use of barrier hoses...but this is just one of those things that kinda popped up after retro fitting had been done for a couple of years.
But keep in mind...barrier hoses in various configurations have been used in various OE vehicle since the 70's.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

TRB on Mon October 08, 2007 9:30 PM User is offlineView users profile

Ice I stand corrected. As you are correct on the original question and compressor oil.

Not sure which is worse. Saying Chick is correct or you!

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com


Edited: Mon October 08, 2007 at 9:31 PM by TRB

iceman2555 on Mon October 08, 2007 10:34 PM User is offlineView users profile

Perhaps...it is not the problem that either Chick or I am correct....perhaps....it is the fact that at your advanced age.....the mind is the first..opps....second thing to go.....but...then you are still much younger than I......mmmm..thanks goodness for those pills......no not those.....the memory ones......

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

TRB on Mon October 08, 2007 10:44 PM User is offlineView users profile

That's why you don't buy us lunch on the corporate card. You're maxed out on "supplements"!

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

iceman2555 on Mon October 08, 2007 10:47 PM User is offlineView users profile

Ahhhh...yes...supplements....the nectar of 'aged' mortals..........yep...for sure.....

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

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