# AC compressor oil



## alanmay0 (Sep 3, 2015)

I have a 1967 GTO with factory air. I recently replaced the condenser, dryer, rebuilt the compressor and replaced the hoses. Now am ready to pull a vacuum and see how well I did. You have told me that this system with the A-6 compressor takes about 3 lbs of R-12 freon. 

Now I need to know how much oil it takes. I have been told that pure mineral oil is ok. This is the mineral oil you can buy at a drug store. So my three questions are

1. Is this mineral oil ok for the system
2. How can I get this oil into the system
3. can I put this oil into the system before pulling the vacuum

Keep in mind that the system is completely installed in the car and I do not want to have to remove the compressor to add the oil. It would be much easier to open one of the hoses and poor the oil in that way. Just don't know if this is possible or what hose to pour it into.

I am assuming that the oil should be poured into the LOW pressure side of the system.

I am not a AC man just doing what I can to keep the cost down. Already approaching 90k.

thanks
alan


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## alanmay0 (Sep 3, 2015)

Gee 42 views and no suggestions. Still hoping for a reply.
thanks
alan


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## 1968gto421 (Mar 28, 2014)

Alan, I would love to be able to help you...but I know squat about A/C systems. Our daily driver mechanic is real good with them. He built a 1932 Buick street rod in his home garage and put A/C in it so I know he knows his stuff andI trust him with the new cars and my GTO on the A/C thing. Sorry. (I know there are guys on this forum who do know...where the H are they?)

You could try posting on the PY forum sponsored by Ames. I know guys there will chime in with help...... Pontiac - Street - PY Online Forums

Hope that helps.


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## Goat Roper (Oct 28, 2014)

I converted mine from R-12 to 134 and the oil came in a small can that went in the same port as the refrigerant.
I did it myself with the help of a how to vid on YouTube.
So far it works just fine.
Used my Gompco medical suction machine for the evac.


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## RT-1 (Mar 21, 2012)

OK, Alan - here's the scoop. First, the mineral oil at the drugstore is NOT the right stuff. Same name - different viscosity and purity. You need A/C oil - 525 viscocity. Here's an example: https://www.oreillyauto.com/detail/...frigerant-oil-12459/mineral-oil/59000/4521683

Second - the system takes a total of 11 ounces. That needs to be distributed throughout the system. To do this correctly, you need to know how much residual oil is in the system. Based on measurements GM did, when you replace the condenser, you lost 1 ounce. When you replaced the dryer, you lost 1 ounce. The evaporator holds about 3 ounces. The compressor should have about 6 ounces. So, procedure is to invert the compressor and drain the oil into a measuring device. If you recover less than 4 ounces, you add 6 ounces to the compressor. 4-6 you match what you recovered with fresh oil up to a total of 6 ounces.

As to where to put it - you need to limit the the amount in the compressor to 6 ounces, but you can pour the rest wherever. It will distribute itself fairly quickly once you start moving refrigerant. 

Once you get the oil in, you need to pull a vacuum and leave it for a while. Don't be in a rush - On R12 systems, I'll leave it in full vacuum overnight. The last thing I want to do is fill a system with $100 a pound refrigerant only to find out I've got a leak. You could even dry fill with nitrogen to a pressure of around 100 psi and leave it for a week and see if it holds. Especially since you said you rebuilt the a/c compressor yourself. The front seal install can be a bit tricky, and again - you don't want to lose that refrigerant.

If you have any more a/c related questions, I'll be glad to help.


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## leeps (Apr 2, 2011)

Alan, did you get this figured out? I am rebuilding the engine in my 69 and I thought replacing the AC Compressor would be a simple thing to do. Remember one of the last lines from My Cousin Vinny where Marissa Tomei says "Oh my God, what a F--kin nightmare!" 

Well, that's how I felt. I think my system was converted to R134 some time ago. Long story short, I am changing the muffler to the compressor for cosmetic reasons, but I have to change the drier or the compressor will have no warranty. R12 is more forgiving and hose clamps can be used, but I believe it is way mroe expensive than R134 and I don't know if it can even be bought in stupid whacko California anymore. (guess where I live?)

R134 is cheaper, but way smaller molecularity, so all of the fittings have to be threaded with 0-rings. I was told the compressor should be drained of all oil because you can't trust how much is in it (especially true if buying a new one). And the only way to do that is with it off the car, then refill before installing on the car because the orifice to fill is so small. Anyway, back to my Marissa Tomei comment. I was just wondering if you got it figured out. I am figuring after buying a compressor, muffler and a drier, THEN taking to a shop to check out and refill with refrigerant, I am looking at $1,000.

Whoopee! But it's there, so it may as well work, right?

Mike


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## alanmay0 (Sep 3, 2015)

Tank you for the information. I have one question for you please. I have already pulled the vacuum on the acunit and it held over night. Now my question is there a way to get the 11 oz of 525 oil in the ac system short of removing the ac compressor? I mean can I just poor it Into the system somewhere?

Thank you in advance
Alan


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