Update... I have questions about how much oil should I leave in the new compressor. You can skip to the math further down.
Got the parts, assembly the new compressor & clutch, took the old compressor out, and drained and measured the oil for both.
The old compressor is super clean inside and it turns by hand no different than the new one. I have zero reasons to believe it failed or that it needs replacement due to internal wear. The neck of the compressor is a totally different story with a lot of damage caused by the clutch pulley. I'm going to post about that in a different thread as it is very unusual and I suspect it was a defective part from the factory.
I decided to follow @aztoyman advice here and not try to do "preventive maintenance" on the AC system ... not replace the condenser just because I have a new one on hand. There is the strong temptation of replacing old parts with new when you have the parts. I'm also not going to mess with the drier for these reasons:
1. there was no internal system failure to require it
2. replacing it will bring more uncertainty about how much oil is in the system/needs added
3. replacing requires condenser removal to gain access to the drier plug that is at the bottom, inviting leaks and adding labor in an area totally different than the compressor
4. the system was open for short time as the pipes were plugged with silicone plugs and taped right after disconnecting from compressor.
Next is to figure out how much oil should I have in the new compressor.
The old rule is to drain & measure the old compressor, then drain the new and add back the same amount drained from the old compressor.
The FSM and Denso manual is saying to still drain and measure the old compressor but then to remove just enough oil from the new one so the remaining oil is the same quantity as in the old compressor before draining.
I did drain both and measure both. What I found out is that you cannot drain ALL the oil from a compressor even if you take the time to turn it, hold it, etc. The oil is design to adhere to the surfaces (good) and it has some viscosity (also good) that will prevent removing all the oil. Flushing the compressor is something that should never be done.
The new compressor is speced by Denso to come w/ 135ml of oil already filled in. I managed to get out 110ml and probably 10ml was lost in the process on drips, runs, coating on the tools and pans. I estimate that the remaining 15ml are coating the many inside components.
This is why the FSM and Denso procedure should be followed with these compressors.
Next is to actually do the math. Here the two trusted sources for how much oil to be removed from the new compressor, and they are differing by 15ml - small but more than 10% of the system total capacity!
FSM formula is: 135+15 - [amount removed from the old compressor]
Denso formula is: 135 - [amount removed from the old compressor]
The question is
why Toyota wants you to remove 15ml (0.5oz) more oil from the new compressor?
All sources I read say that the system can cope with a bit more oil than ideal, the risk being decrease in cooling efficiency. All agree that not having enough oil will eventually damage the compressor. Given that, I'm using Denso formula instead of Toyota. Please let me know if you think Toyota formula is better.
Besides the above in my case things are a bit messier. The shop that evacuated the freon from the system wrote down 12ml (0.4oz) of oil removed, but my visual estimation looking at the actual jar on the machine was more like 30-35ml (1-1.2oz) - I measured the jar diameter and the fluid level change and estimated the jar wall thickness. [Edit] I called the shop and they confirmed that the machine itself does not measure the oil, just separates & collects it. The 12ml was the tech estimate not a measurement. If you do this, it's a good idea to take pics/measure the level before and after and do your own estimation. [End Edit] The oil I removed from the old compressor measured just about 15ml (0.5oz) very little compared to the new compressor, telling me that most of the left oil is distributed around the system, one more reason not to mess with the condenser. One important data point: I forgot to force the compressor to run a few minutes before evacuation - per FSM it helps collecting the oil in the compressor. That might have contributed to the low results. Anyway, the oil in the system is very clear so not a big deal.
Adding the above and some other oil loss on drips when disconnecting/handling the compressor hoses (especially the suction one with the big bulge), and measuring, the total removed oil comes to about 42-50ml (1.4-1.7oz) not including the estimated 15ml residual/non-removable internal compressor oil.
Here is a table from Denso literature with the oil distribution, and the generic rule of thumb for adding oil for each component replacement used by the AC shops:
| Denso | Generic |
| Evaporator | 20% | 1.5-2oz |
| Condenser | 10% | 1oz |
| Dryer | 10% | 1oz |
| Accumulator | | 2oz |
| Compressor | 50% | 1oz |
| Hoses | 10% | 1oz/ea |
So, in my case I want to have left in the new compressor:
50ml - amount drained from the old compressor and during evacuation, etc
15ml - estimated amount of oil I could not drain out of the old compressor.
total 65ml.
Given that there is already 15ml oil I could not drain out of the new compressor, I need to add back 50ml oil in the new compressor.
Have I got it right?
