Replacing AC compressor - Do I need to add oil? Topic is solved

nelaco · Post by **nelaco** » 20 Apr 2022, 10:53

Hi group, the compressor on my SUV with 175k miles seized. I already got a new Nissens from FCP, along with a new receiver/drier. My plan is to take it to a local shop for them to evacuate the refrigerant and flush the system. Then I'll swap the old parts with the new ones and bring it back to the shop to add the refrigerant back.
The new compressor already comes with oil in it, but I am not sure if I need to add any, or do anything else for that matter. Is it this simple or is there more to it?
Thank you in advance.

Post by **SuperHerman** » 20 Apr 2022, 21:29

This gets tricky. If one changes just the compressor the practice is to pour out the oil in the compressor and measure it. Then do the same with the new compressor. Replace so the amount that came from the old compressor is the target amount. The problem is there is oil else where in the system, but you are changing other components and flushing the lines. Assuming the flush got rid of all the oil then the process is simple. Look up the specs for how much oil the system takes, pour out what is in the new compressor and add/subtract to the target specs. Make sure the oil in the new compressor is the correct oil and/or what you are adding is the correct oil.

Call your shop and verify that their flush will rid the lines, and related of all the oil.

nelaco · Post by **nelaco** » 21 Apr 2022, 05:23

This makes sense. Thank you for the quick help. I'll get a can of PAG oil since I'll probably need it. Mine has AC in the 3rd row so it calls for 7 ounces. My son has the car right now so I'll have him take a picture of the label to confirm type of oil. The owner's manual only says "PAG", but I see there are PAG 46, 100, and 150. FCP says both 46 and 100 "fit my car". Hopefully the label will have this info. Tks again!

nelaco · Post by **nelaco** » 25 Apr 2022, 06:58

So the label under the hood is calling for "Volvo PAG oil", and the one from the Nissens compressor indicates it "Contains PAG 46 oil". The Nissens video says (@ minute 6:00) if oil is needed, to make sure to use "oil of the same viscosity as that of the vehicle manufacturer".
Anybody knows if it is 46 or 100 for the xc90? If 100, do I mix it with the 46 in the compressor, or empty the compressor and use only 100?
BTW, I also decided to replace the condenser since I've read it is almost impossible to flush clean.
Thank you all!

Post by **ggleavitt** » 26 Apr 2022, 10:45

Might be something in the attached, at least for component capacities upon replacement. PNs are noted for oil, might be able to cross reference for viscosity (they're old PNs so you will need to find the replacement).

The original 5/6 cylinder compressor is Zexel (Valeo now) with a front mounted solenoid clutch for activating and deactivating the compressor. This is the compressor that you can insert bread ties or tie wraps (my preference) as a first effort when the AC "randomly" stops cooling for a quick fix instead of re-shimming or replacing the clutch or the compressor. Thisi is a pretty common failure over time as the clutch wears and gap gets too wide for the solenoid to pull the clutch down solidly. Description here- viewtopic.php?p=142366

The post MY07 3.2 and V8 models use a Denso variable demand compressor with a side mounted solenoid valve. That valve can get gunked up over time and won't regulate cooling accurately, easy enough to replace in the vehicle after evacuating the refrigerant.

I've done both of the above for repairs (tie wraps on the 05 when I owned it, new solenoid valve on the 06 last summer).

Good luck with your work..

Compressor Replace B5254T2.pdf: (116.46 KiB) Downloaded 342 times

nelaco · Post by **nelaco** » 26 Apr 2022, 11:27

Excellent! Thank you so much. This PDF confirms I should be using PAG 46.
And yes, I am familiar with the clutch/gap issue. I just fixed it on my son's C30 @85k miles..
This one unfortunately has a seized compressor. After 17 years, and 175k miles I can't be too upset. Looks like it will cost me about $450, including shop's charge for evacuating and refilling. Not too bad.
The local shop wanted $1150 and was only replacing the compressor.

Thanks again!

Post by **abscate** » 01 May 2022, 04:12

I went through the same dance trying to figure out pag 46 vs pag 100

Incredibly, one manufacturer had “ brand named “ pag 46 spec oil ‘ PAG 100’

That pdf chart puts it straight.

That’s a great price from that shop

Post by **cn90** » 03 May 2022, 21:40

I replaced the AC Compressor for my 1998 BMW E39 528i in 2016.
We discussed PAG 46 and PAG 100 there too.
Also, the amount of oil needed depends on the extent of the job.
As mentioned above, do NOT trust the mfg, always drain the oil into a clean container, measure and add appropriate amount. For the most part, some oil is left behind in the pipes and other components but not much.
Most of the PAG oil goes back to the compressor when the engine is shut off.

https://www.bimmerfest.com/threads/diy- ... or.924320/

Post by **cn90** » 12 May 2022, 11:20

For AC compressor, since the job is labor-intensive, I usually stick to original mfg name.
In the case of Volvo, likely Zexel brand.

PS: In the 1998 BMW 528i I mentioned above, I put in PAG100 oil in 2016, so far so good...

nelaco · Post by **nelaco** » 12 May 2022, 11:54

I got the Nissens since it is $200 cheaper than Valeo (old Zexel) and has great reviews.

Still waiting for my son to finish his semester and come home so I can fix this. I'll update the group with my notes once done.

Thanks again everyone.