Chevelle Tech - View Single Post - r134a numbers with stock Condenser & replacement POA
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post #32 of (permalink) Old Aug 24th, 19, 12:07 PM
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Re: r134a numbers with stock Condenser & replacement POA

Originally Posted by hjdca View Post
ok, so, I talked to Mike over at Original Air (Tampa, FL), the numbers we are looking at for oil are too much for my aftermarket March P412, (Sanden) compressor. What Mike told me is that for a complete system with a similar Sanden compressor they put in a max of 210 cc oil. He said I could put that in, but, no more.

The numbers we are looking at above are used when replacing just one part in the system, ie. if you replace the condenser, then, it is taking 1 oz. of compressor pump oil with it. If you replace the Evaporator, then, it is taking 3 oz. of compressor pump oil with it. The concept is that you have to replace that oil in those components to keep the right amount of oil in the system.

My understanding now is that if you start with a new system, with all new components, then, all you need is a full compressor of oil and no more oil in the other components. As the system gets used, the compressor oil gets distributed in the various components, so, if you replace one, you have to estimate the amount of oil you lose, so, it can be replaced. That is what the chart is showing you in the Chevelle manual.

So, for example, if you system needs 11 oz., that is 11 oz just for the compressor. You put 11 oz into the compressor, button up the system, vacuum and charge. Your compressor is not specified as only needing 6 oz and the other parts needing 5 oz. In fact, the documentation is telling us that this oil that the compressor needs is then distributed during usage and must be replaced when a new part is introduced.

The March MCH-P412 says it comes with 100 cc of Sanden SP-15 Pag oil. So, now I have to decide if I add another 100 cc of SP-15 to the whole system or not add any at all except the 100 cc that is already in the compressor.

Do I have this right ?
Your Denso compressor should maintain a minimum 30-50 percent of the initial compressor fill amount within the compressor after being charged and run. That's to say if the compressor is removed from the system and drained it would have about half of the 3.38 oz oil charge = 1.64 oz.

The Chevelle A/C Components will then retain a total of 5 oz and add the 50% retained value of 1.64oz = about 6.5 oz = 1.92 cc. So the 200 cc or 6.76 oz recommended would be your target.

If you try to run your system with only the initial compressor oil charge of 3.38 oz on the Chevelle system, you'll soon be replacing that compressor as the components will easily hold and starve your compressor of oil.
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