I just got through replacing everything with the a/c and am going with the VIR conversion as I want to change from R-12.
My question is the A6 compressor is pre-loaded with 3 oz. of PAG 150 and chevys service manual says it takes 11oz..
Were and how do I add more? Will the compressor hold that much?
It is a dry system right now as I replaced everything and have not added any PAG to anything.
And why in the h@ll do the change all the bolts to metric?

 

You only need metric bolts if some of the parts require them or because of a difference in assembly 'fit' if you were to use 'English' fasteners.

If I were swapping to R134a, I would (and I did) swap the compressor for a modern Sanden unit.. The A6 is just another 'old' thing that will fail [eventually] and is inefficient by today's standards. The A6 will function adequately if you choose to stay with it. But, it was designed for R-12 and will not perform as well with 134a.

P.S. Make certain that you flush the system completely {internals of compressor, especially) of ALL mineral oil, if you are swapping over to 134a. 134a and R-12 are incompatible.

 

My OEM compressor lasted 2 years when I switched to R134A. Be careful as some new compressors are sold as "Like Sanden".....they are 2nd rate knock=offs. Pay a little extra and get a genuine SANDEN,,,it will freeze you out!

As for metric stuff...you can use a "very close to size U.S, tap and "clean out" the metric threads to fit U.S. bolts and nuts. Use Tapping Oil/Fluid when re-threading parts
"Bottom Taps work well for metric thread "Blind holes" and for metric thread holes that go all the way thru the metal part.
Usually every 4th metric thread in a threaded hole will be "re-cut" by a U.S Tap. Just make sure the U.S, Tap doesnt fit "loosely" when re-tapping a metric thread....NO guarantees=practice first on spare metric "barrel nuts" you can find at a hardware or Box-store/Lowes-Etc.

 

There are some little known cons to using r134a. Although not as potent as r12, r134a is also a greenhouse gas and needs to be recovered before opening a system. EPA has declared r134a obsolete with the first phase-out starting 1-1-2021. But, you’ll still be able to buy it for a long time. R12 is still readily available on eBay(I got an EPA cert for r12, but nobody ever asked for it. R12 will produce significantly better cooling; especially if it gets very hot were you live. R134a has a narrower tolerance for capacity. Exact volume and pressure not as critical for r12.
Agree with above on benefit of upgrading the compressor.
GM service bulletin recommends suction screen on compressor inlet and inline filter after the condenser.
Best place I found for oil and refrigerant capacities was the sticker that goes on the compressor. The new ACDelco compressors I got came with instructions on calculating the oil amount by which components you are replacing.
The new compressor came with metric threads for the mounting bolts. Procured new bolts to fit but found they were too fat to move around in the adjustment slot. Wound up needing to grind out the slot to make it wider. So really didn’t save any time over re-threading the holes in the compressor.
Add insulation between exhaust and evaporator box. 1’x2’ high-temp stick-on stuff wraps the whole box well enough I didn’t need to actually stick it on for quick reversion in my all-original car.

 

The A6 takes 6 oz, the condenser takes 1 oz, the drier takes 1 oz, and the evaporator takes 3 oz. All add up to 11 oz.
Should not put 11 oz in compressor and expect the oil to distribute like that. Oil can be added to comp thru the oil level plug on the side of the compressor. I think I got a pic here if all worked well. This oil is compatable with R-12 and R-134.

Dom

 

134A and R12 have no compatibility issues. You can literally mix them together without any undesirable effects using an orifice tube system.

It's the oils that have compatibility problems. PAG and mineral oil ARE incompatible with each other. In addition 134A will not carry mineral oil, thereby starving the compressor for lubrication if attempted.
As pictured above ESTER is the oil to use if you don't want to replace all the old hoses and have to flush every drop of mineral oil out to prevent mixture with PAG.

The PAG that comes in the compressor needs to be drained and replaced in any case if you plan on using PAG.
If not them drain the compressor, flush it and replace with Ester oil.
You can blow out the residual mineral oil in the condenser and evaporator (filter drier needs replaced so it will be empty), then put the ester oil in the right places in the right quantities and charge the system with 134A, assuming you are using an orifice tube conversion to replace the VIR.

I have had ester in my A/C for over 10 years, still stock hoses and compressor with an orifice tube system. Works good. I do have the R4 compressor not the A6.

 

I agree 100%. I have mixed them with no problems. Expert told me that that RULE was because they could not seperate them so they could re-cycle.

Dom

 

Thanks for all the information guys.