New Geo Metro compressor

[Tommer2]

Hi All, I’m installing a new compressor and a new drier in my 91 Geo Metro R12 system. Geo calls for three oz of mineral oil. My question is should I add the full three oz to the new compressor? I was thinking if there is some oil in the system already three oz in the new compressor might be too much. What say you? Thanks.

[Cornbinder89]

Nope, Leave the 3 oz in the compressor. The R/D is the one place that oil will likely "pool" and you are replacing that. A little too much id better than too little. 3 oz isn't much and I am surprised that is all it calls for. IIRC my A-6 takes 10 oz!

[Tom Greenleaf]

Welcome and wow, this is just an 18oz system by a chart I use for specs. New should mean really new not a fan of rebuilt units but may not have much choice? Spin oil thru the new compressor on the bench till it comes out I'll say at least 20 revolutions. No telling if this is NOS do that just anyway.

Old one: Measure what comes out of it as best you can the same amount that came out used to say fine with a couple more but such a small capacity that which comes out of any parts replaced even drill a hole in the drier and warm it up plus an ounce. That's my guess not some known spec for what to do. See you just don't know how much oil stopped where when system quit when it was last operational.

It's that or flush out everything, blow it out dry and clean then go by the 3oz spec putting some in compressor and the rest upstream of it so it gets the lube early when making the loop back around.

PS: Lots matter now at the age what has already been done too along the way. Hard to believe nothing was touched at all and just know that replacement parts do NOT always use what was original just FYI chart shows '94>'96 models also used 18oz of 134a jumped to 21oz in '97 and oil (PAG150) up to 3.5oz? Reason I look for that in these years is many vehicles used the R-12 system just retrofitted it new when R-12 ceased use in model year '93 vehicles could be either just that one model year. Good luck with the job,

[Tommer2]

Man you guys are on top of it!!! Thanks.
The only reason I’m replacing the compressor is that it’s leaking at the front seal a little. Cools well but just can’t keep up. I’ll do what you guys say to do. Thanks again.

[Tommer2]

Just another note I’ve had this car since it was almost new,5,000 miles so I know it’s r12. Always cools real well until just recently when I noticed the leak at the front seal area. Thanks.

[Cornbinder89]

Way too much oil will coat the inner surfaces of the evaporator and condenser and reduce the heat transfer, too little will cause the compressor to self destruct in short order spewing parts into the system.
If I have to choose one over the other, I will error on the side of too much and pay the penalty in reduced cooling.
The problem with draining and putting back the same that you drained, is you already know some leaked out with the refrigerant and you don't know how much, so putting the same back will leave you somewhat below where you need to be.
Going back with what the spec calls for might put you slightly above, but no so much over as to cause a problem. You are changing the two main places that oil collects, little is held in the hoses or condenser.
You'd have to well above 10% over on the oil for it to be a problem, and I doubt you would be that with a new compressor and receiver/drier..

[Cusser]

Hi All, I’m installing a new compressor and a new drier in my 91 Geo Metro R12 system. Geo calls for three oz of mineral oil. My question is should I add the full three oz to the new compressor? I was thinking if there is some oil in the system already three oz in the new compressor might be too much. What say you? Thanks.

I'd drain out any that comes with the new compressor. Then I'd flush the compressor twice with a little R12 mineral-type oil, rotating the compressor at least 10 turns, then draining. Then drain the last flush out and add the desired amount of R-12 oil.

I say this because I bought a compressor for my 1988 truck (R-12), and it had PAG oil in it from manufacturer, so I had to flush that out. Back then I had an easy way to check the oil type. You may find compressors with no oil, too much oil, or the right amount and type. But I wouldn't trust any !!!

[Cornbinder89]

^^^^ likely very good advice. On my stuff I am the one going inside and fixing/rebuilding so I know what oil is in them. Now a days you don't know what you are getting, wrong oil and it will not circulate. Better to know what you have than hope!

[Tommer2]

AGAIN Ypu guys are all on it!!! Thanks