This is not OEM I guess, if that means bought from VW/Audi? There are compressors from different brands that fit to my model, and some of them are not prefilled, some has a complete system fill and others are filled to 50 %.
I’m a novice and do not have any really knowledge in the field but if you read manuals and look at official instruction videos from example Denso, they say that you fill the new compressor with same amount as you drained the old compressor with. And also that it matters if you replaced other parts than the compressor. They (and different other sources) also say that it depends if the system was completely flushed or only drained from refrigerant. If the system is completely flushed or if you replace all parts, then you would need to fill the compressor with 250 ml in this case.
So I can’t understand the logic in keeping the prefilled amount regardless of circumstances. If the system is completely flushed then 180 ml would not be enough for example.
My post (#24) was not entirely correct. I forgot to add some important information.
I'm sorry about that.
How to explain so I don't make it more confusing...
The entire system is specified to hold 'x' amount of PAG oil. (I don't know what that amount is off the top of my head.)
Each component of the system has a percentage of the total oil in it. The compressor (being the largest percentage of volume), dryer, condenser. (all this info is listed in the Bentely Manual)
So for example, if you replace the compressor but nothing else. The new compressor is 'pre-filled' with the specific percentage of the total PAG oil volume.
In this case the residual oil left in the other components of the system combined with the 'pre-filled' compressor oil equals the total volume needed.
Does that make sense?
Most proper mechanics will tell you that anytime the sealed a/c system is exposed to the outside environment, a full evacuation (vacuum for minimum of 30 minutes) should be done to remove any moisture and all liquids.
Then at that point with a completely empty system, the total system volume of PAG oil is introduced into the system along with the specified weight of Freon.