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I am trying to drain the correct amount of PAG oil from a new compressor but according to the repair manual I should not drain more than 1.8 oz from the new compressor. The amount of oil I removed from the old compressor was 1.9 oz. Repair manual says (4.6 oz - 1.9 oz = 2.7 oz to remove from new compressor). So the math says remove 2.7 oz while at the same time the note in the repair manual says do not remove more than 1.8 oz. Not sure which is correct and just for additional information the new compressor states that it comes pre-filled with 3 oz of PAG oil. In addition to this I am replacing all of the major components from the A/C system. Additional PAG oil is required if replacing these components but my question is where do I add this extra PAG oil? Would appreciate any help here thanks.
In addition to this I am replacing all of the major components from the A/C system. Additional PAG oil is required if replacing these components but my question is where do I add this extra PAG oil? Would appreciate any help here thanks.
Your confusing me too. When everything is “new” and before the AC compressor is first run, the PAG oil should be in the compressor , usually mostly low side.
Once system is running the oil will “coat” the inside of everything. the hoses , the evaporator, the condenser all of it will end up coated. The system needs enough oil to do all the coating and still have enough oil to run properly.
When you replace a component, your also “losing” the oil that was coated inside it, so if you replace all the components your going to need a full oil charge. (You are cleaning the hoses between components right?)
Yeah I was not sure if I was making any sense but allow me to try and clarify. All of the a/c components are going to be replaced except the a/c lines which I have flushed out. So I will be starting with what I assume is zero oil in the system, the paperwork that came with the new compressor says that it comes pre-filled with 3 oz of oil. So I would be at 3 oz of oil if I installed everything as is, but since I will be replacing the other components how much more do I need to add? The screenshot below is what I have found from a 7th Gen repair/maintenance manual and I'm still not clear on how much total oil is going to be needed in the system.
I just finished some work on my system and, I agree, it is confusing. I have the same information you posted. I finally came to an answer that I can live with....
I think that the directions envision a system whose total amount of PAG oil is 4 and 1/3 oz. That's the maximum amount that can be in the system. So if you were only going to change out the compressor and you add up the totals in the list that already are in the system and have oil in them (condenser - 5/6th oz, evaporator - 1 1/2 oz, hose - 1/3 oz, receiver/dryer - 1/3 oz) you come up with 3 oz. The directions say do not drain more than 1 and 2/3rds from the compressor (if charged). So if you had a compressor that was precharged with 3 oz, and you drained 1 and 2/3rds from it, you would have 1 and 1/3 oz left in the compressor. So you add 3 (from all the other components) and the 1 and 1/3 oz in the compressor, and the total is 4 and 1/3....the maximum amount that can safely be in the system.
So if you were only changing the compressor, you'd still drain out 1 and 2/3rd of an oz, out of a precharge of 3, because there is already 3 oz in rest of the system. If you were changing the compressor and the condenser, you'd still need to have, at a maximum, 1 and 1/3 oz in the compressor and you'd add 5/6 of an oz because the new condenser does not have oil in it. So...always ensure you have, at a maximum 1 and 1/3 of an oz accounted for in the compressor and add any additional oil to the calculation if you are changing out a component of the system.
Everything I see for late model cars says the ac system runs on about 4 oz of PAG. This is how my DIY brain came to this answer and it makes sense to me. Probably BS but I can live with this. The question is can my ac system live with it???
07-18-2019
