On my '88 GT that I just finished restoring and I also completely rebuilt my A/C system, that is, every component and every hard line was cleaned or replaced. All the oil was completely drained, the drier was replaced and the compressor (HR-6) was rebuilt. All o-rings and seals have been replaced to the green o-rings except the shaft seal on the compressor.
From what I can see in the service manual the compressor requires 8 oz of 525 viscosity refrigerant oil. I would like to go with R12 with the option of 134a if I'm forced to. What oil do you recommend that will work for both?
Then, what is the best way to add it? My compressor is dry, should I add a few ounces (oz) directly into the compressor suction port and then add the rest of it in the low side port? Or is it ok to add all 8 oz through the low side port.
Thanks
------------------ Nick D. '88 Fiero GT 5-spd '03 Jetta GLS TDI 5-spd
First of all I would go with the R134. R12 is so expensive and hard to come by. But if you go with R12, yes use the 525 viscosity, R134 uses Pag oil. The complete system takes 8 oz, not just the compressor. I would add 2 oz each to the compressor, the accumulator/drier, condenser, and evaporator. The way it should have been done would be drain the oil from the compressor and measure it, then add the same to the new compressor. I would add the oil to the suction port on the compressor and once it is mounted and all lines connected, turn the "hub" on the compressor 10 times by hand in the direction of rotation. By the way, R134 cools the Fiero sufficiently.
[This message has been edited by notwohorns (edited 05-12-2017).]
Thanks for the info on the oil, I was about to order this Ester can that claims to be compatible with R12. R-134a Ester 8.5oz oil charge
But, I came across a TSB from 2005 by GM, bulletin # 05D-J-114, that states on page three that there are no approved Ester lubricants approved by ACDelco. It looks like mineral oil for R12 and PAG oil for R-134a, each not compatible for the other refrigerant? I have a supply of R12 so I was hoping to use it first but in the future I might be forced to R134a so I was hoping to find an oil that would work with both.
If I understand you guys, there is no oil that will work for both refrigerants?
Correct, 525 viscosity mineral oil for R-12, or PAG for R-134A. One is not compatible with the other, and cross contamination can cause problems. PAG viscosity varies by compressor. A rebuilt 80's vintage compressor is going to be fairly worn out by now and PAG150 is going to be the best bet.
R-134A is going to be cheaper and easier to service in the long run. I also have R-12 sitting in a box, but at this point I'm just saving it for if I buy and need to service a car that still has a functional R-12 system.
If you set it up for R12 now and switch to R134 later the system would have to be flushed out and a new accumulator/dryer replaced. The compressor would have to come off, drained, and then Pag oil added.
POE (polyester oil) is compatible with R12 and 134a and it can mix with mineral oil which is why it is recommended for an R12 conversion that was not flushed or a total teardown. If you run Ester you would technically be able to switch from R12 to 134a if you chose to do so. PAG is the best oil for 134a and I think the only oil Harrison recommends for their compressors. POE is the next best oil next to PAG but it can break down into acid if moisture becomes present in the system (not likely with a new accumulator and good vacuum).
Since you have a clean system I'd run 134a with PAG and hang onto or sell the R12.
BTW I did not flush my systems, so I am currently running POE in my 88GT (HR6) and 88 coupe (V5 compressor) without any issues.
[This message has been edited by 88cryan (edited 05-18-2017).]
I've had the GT since spring 2011, I converted it to 134a that summer, so 6 years. The 88 coupe only a month (new to me car).
I don't have a favorite brand, just bought what the parts store had (a/c pro in a white bottle). I googled poe oil and found an 8 ounce bottle with dye (I do recommend dye added) for $15.
[This message has been edited by 88cryan (edited 05-19-2017).]
