Sparkee

I have a '95 Suburban with rear AC, the AC has never worked since I have owned it. I am getting ready for a road trip and decided to get the AC working. I am replacing the compressor, receiver/drier, orifice tube, rear expansion valve and the O-rings for all the joints that I could get apart.

1. To lubricate the new O-rings, what kind of oil do I use? I've seen some places say to not use PAG oil and to use R-12 ester oil instead. Is this true and why?

2. The spec for oil capacity is 11 oz., where exactly do I add it? Do I put all 11 oz. in the compressor? Or do I put some in compressor and some elsewhere? If so where?

3. I read that I should use PAG 150 oil, is that the correct oil? Do I add all liquid oil, or do I use some of the oil charge cans?

Thanks and have a good one!

in2pro

Welcome to the forum...
Use the PAG oil that is rated for the refrigerant and the system you are going to use to lightly coat the o-rings...I would guess you are going to use R134 since R12 is not readily available....
When I did the AC system in our mini-van the kit came with several sizes of o-rings, be sure to take the time to match up the correct size o-rings for the ones you will need to replace and replace them as you get to them don't assume they are all the same

The compressor will have a certain amount of oil already in it, you will need to add some to the dryer, and to the condenser...
What I did to make the job easier was to do all the work myself, including the evacuation of the system so I could verify that I had no leaks. Then I took it to a shop to have them charge it since often times the charge needed is a size you're not going to find in a just right size can... (you do not want to over charge the system) when the shop does the charge they can also put the right amount of oil in also....

Sparkee

Thanks for the welcome and the response. The truck came from GM with R134a from the factory. The new components came with new O-rings, I got an O-ring kit for the remaining locations in the lines.

The new compressor came dry, no oil installed. I found the oil specification for the system to be PAG 150 oil, 11 oz. since I have rear AC. The compressor will not hold any where near 11 oz. of oil, hence the dilemma where to put the rest and how much. I guess I can add whatever the compressor will hold and split the rest between the drier and condenser.

I have read on multiple sites to not use PAG oil to coat the O-rings. The details were sketchy, something about capturing moisture and causing corrosion where the O-ring might be exposed to outside air. Have a good one!

73shark

The oil is divided between the compressor, condenser, evaporator, and receiver/dryer. I'd check w/ a dealer as it should be in the factory service manual. I suspect that it's in the 2-3 oz range for the compressor. The other components should have retained their oil unless removed and emptied.