A/C Oil question

[Sam71395]

Hi everyone, sorry this doesn't pertain to a square body, this is about my 69 Chevelle. I am in the process of recommissioning the air conditioning in it. It has the factory A6 compressor, I am in the process of adding pag oil to the system, i drained the oil out of the compressor and put the same amount back into it, my question is that do i need to add oil to the other parts like the condenser and the receiver drier, or is the amount I drained out of the compressor all that is needed for the whole system. thank you in advance

 

[75gmck25]

I don’t recall the specific rule of thumb, but if you have flushed the system you need to add more than just the oil in the compressor. Did you replace any other components?

A very general estimate is that the system has about 2-4 ounces in addition to the oil in the compressor, but that assumes all the oil has been flushed.

 

[Sam71395]

I actually bought a complete working r12 system from a 69 el Camino, so the components aren’t new. I’m converting it to r134a, if I remember correctly pag oil for r134a isn’t compatible with the old mineral oil, so I probably should flush the rest of the system right

 

[75gmck25]

You are correct, mineral oil was used in older R12 (Freon) systems, but R134a usually uses PAG oil. PAG and mineral oil do not mix.

You need to use A/C flush, followed by compressed air, to clean the entire system. You will need to disassemble all the parts, including the orifice and the compressor, and then flush each part. Replace the orifice (very cheap part) and filter/drier (also called an accumulator), and use green o-rings to replace the old black ones.

The filter/drier is replaced any time you open the system, because it is there to filter and absorb moisture.

Do you have the R134a gauges and a vacuum pump? If you add the oil and get it all assembled, you can probably just pay a shop to recharge it with R134a. Most of the time the R134a amount will be about 75% of the recommended ounces of R12. From there the shop needs to check the gauges to determine if it needs more.

 

[Finkaire]

PAG Oil is a corrosive and may damage the evaporator. Only use an ESTER Oil in a retrofit system using 134a in an original R12 system. Drain oil, install a new accumulator and swap out the orifice tube only if it removes easily. 10 ounces is what is recommended for the A6 compressor.

 

[75gmck25]

PAG oil can cause corrosion issues, but many new compressors require it to maintain the warranty. However, it sounds like the OP is using the original A6 compressor.

POE (ester) is often used for a retrofit application, and it should work fine for this application.

The orifice may not need replacement, but it’s hard to flush the evaporator without removing the orifice. Removal tools often mangle the plastic orifice, and it’s a really cheap part to replace ($2-$3).

 

[electoqute]

69 should be the big brass stone instead of the plastic tube. 78 or 79 is about the time they started using the plastic orifice tubes. 134 is the reason for the change in design. It needs the smaller valving. Although the the brass is reusable and doesn't break down from heat, it's harder to tell if it's clogged. Heat is why you should replace the plastic tube every time you open the system. Left is original 73. Right is retro for 134

 

[electoqute]

Couple different views