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New member intro/need advice on rebuilding my AC system

npbassman on Mon July 11, 2011 4:27 PM User is offline

Year: 1993
Make: Chevy
Model: Corvette
Engine Size: 5.7L
Refrigerant Type: R12
Ambient Temp: 90
Pressure Low: 0
Pressure High: 0
Country of Origin: United States


I'm Mike and this is my first post. I have a 1993 Corvette. The car was purchased with the stock R12 system in non-working condition and I have recently decided to repair it.

Here is how the system stands as of today. I definitely need a new compressor as I found black sludge all over the bottom of the it (and the drivers side front sterring knuckle) when I bought it. I also need an new accumulator, orifice tube, and I suspect that a new condensor is recommended due to the compressor grenading like that. That said, if you think a really good flush would save my condensor I'd be happy to save the cash. I have carefully removed all of the fluid lines, taped the ends, and cleaned the grease off of them. I plan to flush them individually and then reseal them until I reinstall them on the car. The only items on the car are the evaporator core (which I was not planning on replacing) and the aforementioned condensor. Both have been taped off even though I realize that the system has been open for probably some time.

I am an DIYer and this is my first AC system. That said, I think I have a pretty good handle of what I need to do to get it running again but I definitely need some guidance to make sure I do it right. My first question is, should keep it on R12 or convert to R134a? I'm leaning towards the conversion as that seems to be the recommendation if you need to redo/rebuild an old R12 system. Second, assuming the recommendation of the experts here is conversion, I have these questions:

- Should I use PAG or Ester to lubricate the newly converted R143a system?
- I know exactly how much R12 and mineral to put into the car (via FSM) and I know that R134a is 10-15% less than the total of R12 but exactly how much Ester or PAG do I put in? Is there a formula for this?

Thanks everyone!


Dougflas on Mon July 11, 2011 5:03 PM User is offline

If you plan to do it yourself, spend 30 bucks and do the EPA test. Then buy R12 (available on flea bay all the time) and keep it R12. Use 525 visocity mineral oil. You'll be miles ahaead keeping it stock in my opinion.

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