I will be installing a new AC compressor and receiver drier this weekend. My specific question to start with is this: Which PAG oil spec do I use for the oil? I believe it's PAG 150, but would like to be sure. Here is what I plan to do based on the workshop manual and various forum threads I've found. I have attached a pdf from another thread that was helpful.

The Denso compressor I got (brand new, not rebuilt) says it contains the correct amount of oil, but I think it assumes a brand new install on a brand new system, so it might contain too much oil. I also do not know if it is "shipping oil" or regular PAG oil, so I plan to pour it out and use new PAG oil as per the workshop manual instructions.

According to the workshop manual (see attached PDF), system oil capacity is 180 ml, and I should assume that 90 ml is still in the system inside the various components, and is considered unrecoverable. That leaves 90 ml to add back to the now-empty new compressor.

So here are the steps I'll take. Please weigh in to let me know if this sounds right, or if I'm missing anything!

1. Take the car to my local Ford dealer and have them evacuate what's left of the freon.
2. Take the car home.
3. Remove the compressor and receiver/drier
4. Pour out the shipping oil from the new compressor
5. Assume that there is 90 ml of PAG oil still in the system, as per the workshop manual (see attached PDF).
6. Add 90 ml (about 3 oz.) of new PAG oil to the compressor.
7. Install the compressor & receiver drier using the existing service connector plate and new O-rings.
8. Leave the compressor unplugged
9. Take the car back to my buddies at Ford and have them plug in the connector, recharge the system using only freon (no additional PAG oil).

I appreciate any feedback. Thank you!

 

Follow the directions in the attached PDF as they are the correct steps.

There is no need to leave the new compressor unplugged as the transducer on the pipe from the compressor to the condenser tells the PCM there is no refrigerant pressure, so the PCM does not engage the compressor clutch.

 

Ok, thank you. Is PAG 150 the correct spec?

One other thing that's bugging me about the directions in the PDF is that is wants me to measure the amount of oil recovered during evacuation, and measure the amount of oil I pour out of the old compressor. I'm not sure why. There's no way to know if the correct amount of oil was present to start with, and if the capacity is 180 ml, and they assume that 90 ml is left behind as unrecoverable, wouldn't that leave 90 ml for me to add to the new compressor? Regardless of how much is recovered, and how much I pour out of the old compressor?

 

The correct compressor lubricant is Polyalkyleneglycol (PAG), however there are three types based on viscosity. Since the Workshop Manual for the X308 doesn't distinguish the viscosity for PAG, it would be best to probably go with the PAG 100 as it's the medium viscosity that's most commonly used.

Be sure to lubricate the new o-rings for the compressor with PAG when you install them.

 

Sorry, I forgot to add about the PAG oil quantity. The entire system is designed to hold 160 - 200 ml, but since you are only replacing the compressor and drier, you should add back the same amount of oil that came out of the old compressor to the new one.

There is no need to add additional PAG oil for the receiver/drier.

 

Very helpful, thank you. Further research reveals that there is a tag on the new compressor itself that says ND Oil 8. Google tells me that this is a PAG 46 oil. Denso instructions say that theirs is not a shipping oil, but is the actual PAG oil that I’m supposed to use, so I can use it to match the amount of oil that I pour out of the old compressor. Learning as I go here, and I appreciate the help. I tend to overthink things until I reach a level of understanding that I’m comfortable with.