I'm putting in a completely new (every part new, nothing re-used) A/C system with a delco compressor.

The documentation calls for 5 oz mineral oil (1987 info). Given I'm running r134a, I'll use PAG, but how much? Same as mineral oil charge or should it be lower or higher?

I know the refrigerant charge is about 80% of the R12 charge, but does the same apply to the oil charge?

Also, in my case I've converted to serpentine, does the service manual call out the same oil charge on the serpentine setup as the v-belt setup?

Thanks!

 

Should be roughly the same amount... most of it hangs out in the accumulator/dryer and the compressor.

I usually pour about 3 oz into the suction port of the compressor (look at the lines: the port that the large one hooks up to) and the other 2 into the accum. I use the medium weight, something in the 75 - 100 range as they usually spec it; not the 45, not the 150.

 

Per this document, I'm reading 8oz of oil for both years.
Fill your compressor with about 3-4oz, pour the rest in your new accumulator/dryer. Remember to lightly lubricate your new o-rings with oil.

Use PAG46 if EVERYTHING is new as you specified. PAG150 is the older oil for '94 up, and it was found PAG46 has better lubrication for longevity.


Remember to pull a vacuum on it for a minimum of 30 minutes, and check for leaks, then fill. Use 20% less R134A than what R12 is called for in the original system.


For those reading this article - PAG oil is NOT compatible with the mineral oil that was used in the R12 systems. Use Ester oil instead.
ONLY add what you take out. Adding more oil in the system reduces the cooling efficiency, and can cause leaks.


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